AutoLogicTools code library
OBD-II Trouble Codes
Look up OBD-II trouble codes with plain-English explanations, common causes, symptoms, diagnostic steps, repair cost ranges, and links to the AutoLogicTools Repair Cost Estimator.
Powertrain (P codes)
203 codes published.
Fuel Volume Regulator Control Circuit/Open
The PCM has detected an open in the control circuit for the fuel volume regulator — the valve that meters how much fuel the high-pressure pump delivers to the rail. On direct-injection and diesel engines this regulator sets fuel rail pressure, so an open control circuit can mean the PCM can't regulate pressure properly. The usual causes are wiring, the connector, or the regulator (suction control valve) itself.
Read this code'A' Camshaft Position Actuator Circuit (Bank 1)
The intake camshaft position actuator on bank 1 has an electrical fault — the PCM is either not seeing the response it expects from the VVT solenoid, or the circuit itself is open or shorted. Almost always an oil-related issue at the root.
Read this codeCamshaft Position A — Timing Over-Advanced or System Performance (Bank 1)
The intake camshaft on Bank 1 is more advanced than the engine computer commanded. Most often caused by a stuck variable valve timing (VVT) solenoid or dirty engine oil. Address promptly — neglected timing issues can damage the engine.
Read this codeCamshaft Position A — Timing Over-Retarded (Bank 1)
The intake camshaft on Bank 1 is more retarded (lagging) than the engine computer commanded — the opposite of P0011. Most often a stuck VVT solenoid or dirty engine oil preventing the cam from advancing on command.
Read this code'B' Camshaft Position Actuator Circuit (Bank 1)
The exhaust camshaft position actuator on bank 1 has an electrical fault. The PCM is sending a command to the exhaust VVT solenoid and not seeing the electrical response it expects — usually because of oil contamination, a failed solenoid, or wiring damage.
Read this codeCamshaft Position B — Timing Over-Advanced or System Performance (Bank 1)
The exhaust camshaft on Bank 1 is more advanced than the engine computer commanded. Most often caused by a stuck VVT solenoid on the exhaust cam, dirty engine oil, or a stretched timing chain on high-mileage engines.
Read this codeCamshaft Position B — Timing Over-Retarded (Bank 1)
The exhaust camshaft on Bank 1 is more retarded than the engine computer commanded. The 'B' camshaft is the exhaust cam on dual-VVT engines. As with all over-retarded cam codes, dirty oil or a stuck VVT solenoid lead the suspect list.
Read this codeCrankshaft Position — Camshaft Position Correlation (Bank 1, Sensor A)
The relationship between the crankshaft and intake camshaft on Bank 1 is outside the expected window. Often a stretched timing chain — known issue on Hyundai/Kia 2.4L Theta II, BMW N20/N26, Audi 2.0T, and other timing-chain engines. Don't ignore it.
Read this codeCrankshaft Position — Camshaft Position Correlation (Bank 1, Sensor B)
The relationship between the crankshaft and exhaust camshaft on Bank 1 is outside the expected window. Same root causes as P0016 — often a stretched timing chain. Don't ignore it.
Read this codeCrankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A)
The PCM compared the crankshaft position to the bank-2 intake camshaft position and found them out of sync beyond what variable valve timing should produce. Usually means the timing chain on bank 2 has stretched, the phaser is mechanically off, or the cam sensor is reading incorrectly.
Read this codeCrankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)
The PCM compared the crankshaft position to the bank-2 exhaust camshaft position and found them out of sync beyond the VVT operating range. Almost always a mechanical timing problem — chain stretch, worn phaser, or a failing exhaust cam sensor on bank 2.
Read this code'A' Camshaft Position Actuator Circuit (Bank 2)
The PCM is commanding the intake-camshaft VVT solenoid on bank 2, but the electrical feedback it's getting back doesn't match what it expects — usually an open, short, or wiring fault in the solenoid circuit on the bank-2 side of the engine.
Read this code'A' Camshaft Position Timing Over-Advanced or System Performance (Bank 2)
The intake camshaft on bank 2 isn't holding the timing position the PCM commanded — it's reading further advanced than expected. The electrical side of the VVT solenoid is fine; the camshaft itself isn't responding the way it should.
Read this code'B' Camshaft Position Actuator Circuit (Bank 2)
The PCM detected an electrical fault in the exhaust-camshaft VVT solenoid circuit on bank 2. 'B' designates the exhaust cam — the one that controls when the exhaust valves open relative to crankshaft position.
Read this code'B' Camshaft Position Timing Over-Advanced or System Performance (Bank 2)
The exhaust camshaft on bank 2 is sitting further advanced than the PCM commanded — the solenoid is responding electrically, but the cam itself isn't tracking the commanded position. Usually oil, phaser, or chain related.
Read this codeFuel Rail/System Pressure Too Low
The fuel pressure at the rail is sitting below what the PCM is commanding under load. On direct-injection engines, this almost always points at the high-pressure fuel pump (HPFP) — not a sensor and usually not the low-pressure pump in the tank.
Read this codeFuel Rail/System Pressure Too High
The opposite of P0087. Rail pressure is sitting above what the PCM is commanding, which usually means the system can't bleed pressure off — most often a stuck or stuck-closed fuel pressure regulator on a direct-injection engine.
Read this codeFuel Pressure Regulator 1 Performance
The fuel pressure regulator isn't doing what it's been told to do — pressure isn't responding to command changes the way the PCM expects. Different from P0087/P0088 because this one flags the regulator specifically, not the rail pressure outcome.
Read this codeMass or Volume Air Flow Circuit Malfunction
The general mass airflow (MAF) circuit code — the PCM has seen a fault in the MAF sensor circuit that doesn't fit the more specific low, high, or intermittent patterns. Most often a dirty sensor, a wiring or connector problem, or unmetered air entering the intake.
Read this codeMass Air Flow Sensor Range/Performance Problem
The engine computer detected that the mass airflow (MAF) sensor reading doesn't match expected values based on throttle position and engine speed. Most often caused by a dirty MAF sensor — cleaning resolves a large share of cases.
Read this codeMass Air Flow Sensor Circuit Low Input
The engine computer detected that the mass airflow (MAF) sensor signal is reading too low — often because the sensor is disconnected, the wiring is damaged, or the sensor itself has failed. The engine may run rough or stall.
Read this codeMass or Volume Air Flow Circuit High Input
The mass airflow (MAF) sensor is reporting more airflow than the PCM thinks is physically possible. Two main causes: unmetered air sneaking into the engine after the sensor, or a contaminated sensor over-reporting.
Read this codeMass or Volume Air Flow Circuit Intermittent
The mass air flow (MAF) signal is cutting in and out. Unlike the steady MAF circuit codes, P0104 is the intermittent one — the sensor works most of the time, then briefly drops or spikes before recovering. That on-again-off-again behavior usually points at a connector or wiring problem, MAF contamination, or electrical noise rather than a flat-dead sensor, and it can make the engine hesitate or stumble unpredictably.
Read this codeIntake Air Temperature Sensor Circuit Malfunction
The PCM has flagged a general fault in the intake air temperature (IAT) sensor circuit — the signal is present but not behaving the way a healthy thermistor should. On a surprising number of engines, the IAT element lives inside the mass airflow sensor, which is why this code so often ends up being a MAF job.
Read this codeIntake Air Temperature Sensor Circuit Range/Performance
The IAT sensor is still sending a signal that's electrically valid — it's not pinned high or low — but the value doesn't make sense for the conditions. This is the 'plausibility' code: the number is in range, but it disagrees with what the rest of the engine is reporting.
Read this codeIntake Air Temperature Sensor Circuit Low Input
The IAT sensor signal voltage has dropped below the PCM's minimum threshold — which the computer reads as impossibly hot intake air. It's the mirror image of P0113: where that code means the circuit looks open, P0112 almost always means the signal is shorted to ground.
Read this codeIntake Air Temperature Sensor Circuit High Input
The intake air temperature (IAT) sensor signal is reading higher than the PCM's normal operating range, usually pointing to an open circuit, a failed sensor, or a wiring problem.
Read this codeIntake Air Temperature Sensor Circuit Intermittent
The IAT signal is dropping out or jumping erratically rather than failing outright — present one moment, gone the next. Intermittent codes are the hardest of the IAT family to pin down because the fault often isn't happening while the car is sitting in front of you.
Read this codeEngine Coolant Temperature Sensor Circuit Malfunction
The PCM is reporting a generic circuit fault on the engine coolant temperature (ECT) sensor — the signal is unusable for fueling calculations. Because the PCM uses coolant temp to set cold-start enrichment, a bad signal can cause hard cold starts, rich running, or stalling shortly after startup.
Read this codeEngine Coolant Temperature Sensor Range/Performance
The ECT sensor is reporting a temperature value that's within its electrical range but doesn't track engine warmup correctly. The sensor isn't electrically broken — it's drifted or sluggish, telling the PCM the wrong story about what the engine is actually doing.
Read this codeEngine Coolant Temperature Sensor Circuit Low Input
The engine coolant temperature (ECT) sensor signal is reading lower than the PCM expects — usually a short to ground in the circuit or a failed sensor pretending the engine is unrealistically hot.
Read this codeEngine Coolant Temperature Sensor Circuit High Input
The ECT sensor signal is reading higher than the PCM expects — usually an open circuit, a broken sensor, or a disconnected connector that makes the engine appear permanently cold.
Read this codeEngine Coolant Temperature Sensor Circuit Intermittent
The ECT sensor signal is dropping in and out — not cleanly failed, just unreliable. The connector is flaky, the wiring is chafing, or the sensor itself is on the way out. Intermittent codes are the hardest to chase because the signal looks fine half the time.
Read this codeThrottle/Pedal Position Sensor 'A' Circuit Range/Performance
The throttle position sensor is reporting a value that's electrically valid but doesn't line up with what the PCM expects based on pedal input, RPM, and airflow. On most electronic throttle vehicles, this is a contaminated throttle body or a tired TPS — not always the actuator motor itself.
Read this codeThrottle/Pedal Position Sensor 'A' Circuit Low Input
The throttle position sensor signal is pegged near zero volts no matter where the pedal is. This is an electrical fault — usually an open ground, broken signal wire, or shorted-internal sensor — not a contamination issue like P0121.
Read this codeThrottle/Pedal Position Sensor 'A' Circuit High Input
The throttle position sensor signal is pegged near the 5V reference voltage no matter where the pedal is. Mirror of P0122 — usually a short to reference voltage, an open ground at the sensor, or a failed-internal-shorted sensor.
Read this codeInsufficient Coolant Temperature for Closed Loop Fuel Control
The engine isn't reaching the coolant temperature it needs to switch into closed-loop fuel control, so the PCM keeps running on its richer warm-up program. Nine times out of ten the culprit is a thermostat stuck open or a coolant sensor reading colder than reality — both cheap to fix, but worth catching because the side effects are poor fuel economy and a heater that never gets hot.
Read this codeCoolant Temperature Below Thermostat Regulating Temperature
The engine isn't reaching its normal operating temperature in the expected amount of time. The most common cause is a stuck-open thermostat. The car is drivable, but fuel economy and emissions will suffer.
Read this codeO2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
The upstream oxygen sensor on Bank 1 is reporting a voltage that's too low for too long. The sensor may be reading stuck-lean, the wiring may be shorted to ground, or an exhaust leak may be letting in extra air.
Read this codeO2 Sensor Circuit High Voltage (Bank 1, Sensor 1)
The upstream oxygen sensor on Bank 1 is reporting a voltage that's too high for too long. The sensor may be reading stuck-rich, the wiring may be shorted to power, or the engine may actually be running rich.
Read this codeO2 Sensor Circuit Slow Response (Bank 1, Sensor 1)
The upstream oxygen sensor on Bank 1 is responding too slowly when the air-fuel ratio changes. Almost always caused by an aging sensor that has lost the ability to switch quickly. Replacement resolves nearly all P0133 cases.
Read this codeO2 Sensor Circuit No Activity Detected (Bank 1, Sensor 1)
The upstream oxygen sensor on Bank 1 isn't switching at all — the signal is flatlined. Often caused by a disconnected sensor, broken wire, or a failed heater that prevents the sensor from reaching operating temperature.
Read this codeO2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
The internal heater for the Bank 1 upstream oxygen sensor failed. The sensor still works once exhaust heat brings it up to temperature, but it takes longer — meaning slower closed-loop operation and worse cold-start emissions.
Read this codeO2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
The downstream oxygen sensor circuit on bank 1 isn't behaving the way the PCM expects — the generic bank-1, sensor-2 circuit fault (the specific low- and high-voltage versions are P0137 and P0138). Either the sensor itself is failing, the wiring is faulty, or the catalyst has changed how exhaust flows past the sensor.
Read this codeO2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
The downstream oxygen sensor on bank 1 is reporting a voltage that's stuck low — sitting near zero and refusing to rise. The usual culprits are a signal wire shorted to ground, an open circuit, an exhaust leak pulling in fresh air, or a worn-out sensor.
Read this codeO2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
The downstream oxygen sensor on bank 1 is reporting a voltage that's stuck high — pinned near the rich end of the scale and staying there. Usually the sensor signal wire has shorted to a power source, the sensor is contaminated, or the engine genuinely is running rich.
Read this codeO2 Sensor Circuit Slow Response (Bank 1, Sensor 2)
The downstream oxygen sensor on bank 1 still works, but it reacts too slowly. The PCM ran a response-time test, forced a change in exhaust mixture, and the sensor took longer than allowed to follow it — the classic signature of a 'lazy', aging sensor.
Read this codeO2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)
The downstream oxygen sensor on bank 1 isn't producing a signal at all — the voltage is flat, stuck at a single value, or the PCM sees no response when it would expect one. Different failure mode from P0136 (low voltage): no signal, not a low one.
Read this codeO2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
The internal heater for the Bank 1 downstream oxygen sensor failed. The sensor monitors catalyst efficiency rather than fuel trim, so driveability is unaffected — but the code prevents emissions test compliance.
Read this codeO2 Sensor Circuit Low Voltage (Bank 2, Sensor 1)
The upstream oxygen sensor on bank 2 is reporting a voltage stuck near zero — meaning either the sensor sees a constantly lean mixture, the sensor itself has failed, or there's a wiring break between the sensor and the PCM.
Read this codeO2 Sensor Circuit High Voltage (Bank 2, Sensor 1)
The bank 2 upstream oxygen sensor is reporting voltage stuck high — usually around or above 0.9V — which means the sensor is seeing a rich exhaust mixture, has been contaminated, or has been short-circuited to a voltage source. Different problem set from P0151, even though they sit on the same connector.
Read this codeO2 Sensor Circuit Slow Response (Bank 2, Sensor 1)
The upstream oxygen sensor on bank 2 is switching too slowly. It still works, but it has gotten lazy — it no longer flips between rich and lean fast enough for the PCM to trim fuel accurately. This is the bank-2 mirror of P0133, and on a high-mileage engine an aged sensor is the usual answer, though an exhaust leak or contamination near the sensor can mimic it.
Read this codeO2 Sensor Circuit No Activity Detected (Bank 2, Sensor 1)
The upstream oxygen sensor on bank 2 has gone flat — the PCM sees no switching activity at all, just a stuck or dead signal. Unlike slow response (P0153), this is the bank-2 mirror of P0134 and means the sensor has effectively stopped reporting, often from a failed sensor, a dead heater, an open circuit, or a wiring problem. The engine falls back to open-loop fuel control, so expect worse economy.
Read this codeO2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
The internal heater in the upstream oxygen sensor on bank 2 isn't drawing the current the PCM expects. Either the heater element has failed, the supply or ground wire is broken, or the PCM driver isn't switching the circuit on.
Read this codeO2 Sensor Circuit Malfunction (Bank 2, Sensor 2)
The downstream oxygen sensor circuit on bank 2 isn't behaving the way the PCM expects — the generic bank-2, sensor-2 circuit fault (the specific low- and high-voltage versions are P0157 and P0158). Same fault pattern as P0136, but on the cylinder bank that does not contain cylinder 1 — and the labor estimate often runs higher because of access.
Read this codeO2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)
The downstream oxygen sensor on bank 2 is reading persistently low — a steady lean-looking voltage that won't come up. As the bank-2 mirror of P0137, the usual suspects are an exhaust leak near the sensor letting in outside air, a genuine lean condition, or a failed sensor or wiring fault. Because this is a post-catalyst sensor, the driveability impact is usually small, but it can muddy catalyst monitoring.
Read this codeO2 Sensor Circuit High Voltage (Bank 2, Sensor 2)
The downstream oxygen sensor on bank 2 is reading persistently high — a steady rich-looking voltage that won't drop. As the bank-2 mirror of P0138, the usual causes are a genuinely rich condition, a sensor or wiring fault (a short to voltage or a contaminated sensor), or coolant/fuel contamination. Because it's a post-catalyst sensor, driveability is often unaffected, but a real rich condition behind it can foul plugs and overheat the converter.
Read this codeO2 Sensor Circuit Slow Response (Bank 2, Sensor 2)
The downstream oxygen sensor on bank 2 is responding too slowly. It's the bank-2 mirror of P0139 and the lowest-stakes of the bank-2 O2 codes: a rear sensor that has gotten lazy. An aged sensor is the usual cause, and because this sensor mainly watches catalyst efficiency rather than trimming fuel, the practical impact is small — mostly a check engine light and a failed emissions test.
Read this codeO2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2)
The downstream oxygen sensor on bank 2 isn't producing any signal — the voltage is flat or stuck at a single value. Same failure mode as P0140, but on the cylinder bank that does not contain cylinder 1, with the same bank-2 labor premium.
Read this codeO2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)
The heater inside the downstream oxygen sensor on bank 2 isn't drawing the current the PCM expects. The sensor itself may produce a signal, but the heater that brings it to operating temperature has failed or has a wiring issue.
Read this codeFuel Trim Malfunction (Bank 1)
The PCM is reporting fuel trim on bank 1 is out of range, but unlike P0171 (lean) or P0172 (rich), this code doesn't commit to which direction. Most readers find this code after looking at P0171 or P0172 first — the diagnostic path here forces an extra step.
Read this codeSystem Too Lean (Bank 1)
The engine computer detected that Bank 1 is running with too much air or too little fuel. The check engine light is on and you may notice rough idling or hesitation, but the car is usually still drivable.
Read this codeSystem Too Rich (Bank 1)
The engine computer detected that Bank 1 is running with too much fuel or too little air. The check engine light is on; you may see black exhaust smoke, smell fuel, and notice rough idling or poor fuel economy.
Read this codeFuel Trim Malfunction (Bank 2)
The PCM has decided fuel trim on bank 2 is out of acceptable range — but unlike P0174 (lean) or P0175 (rich), this code doesn't commit to which direction. The first diagnostic question is whether the trim is being pulled lean, pushed rich, or oscillating between them.
Read this codeSystem Too Lean (Bank 2)
The engine computer detected that Bank 2 is running with too much air or too little fuel. Same condition as P0171, but on the opposite side of a V-configured engine. Only applies to V engines.
Read this codeSystem Too Rich (Bank 2)
The engine computer detected that Bank 2 is running with too much fuel or too little air. Same condition as P0172, but on the opposite side of a V-configured engine. Only applies to V engines.
Read this codeFuel Composition Sensor Circuit Malfunction
The flex-fuel composition sensor circuit has faulted. This is a flex-fuel (E85-capable) vehicle code — the sensor tells the PCM how much ethanol is in the tank, and when it drops out the engine falls back to a fixed assumption that can hurt cold starts and driveability, especially on high-ethanol blends.
Read this codeFuel Composition Sensor Circuit Range/Performance
The flex-fuel composition sensor is responding, but its ethanol reading doesn't make sense to the PCM — it's out of the expected range or it isn't moving the way it should after a fuel-up. This is the 'plausibility' version of the flex-fuel sensor codes, a step beyond a simple dead-circuit fault.
Read this codeFuel Composition Sensor Circuit Low
The flex-fuel composition sensor's signal has dropped to the bottom of its range — a circuit-low fault, usually a short to ground, a failed sensor, or a broken signal wire. On a flex-fuel vehicle this is the PCM saying it can no longer read how much ethanol is in the tank.
Read this codeFuel Composition Sensor Circuit High
The flex-fuel composition sensor's signal has climbed to the top of its range — a circuit-high fault, most often an open circuit, a loss of ground, or a failed sensor. It's the mirror image of P0178: the same sensor, same flex-fuel system, but the signal is stuck high instead of low.
Read this codeFuel Rail Pressure Sensor Circuit
A general circuit fault on the fuel rail pressure (FRP) sensor — the PCM can't get a reliable reading from the sensor. This is a sensor/electrical code, not a 'pressure is wrong' code like P0087 or P0088.
Read this codeFuel Rail Pressure Sensor Range/Performance
The fuel rail pressure (FRP) sensor's reading is plausible on its face — not pegged high or low — but it's drifting away from what the PCM expects based on other inputs. This is the 'something's off' code in the FRP sensor family.
Read this codeFuel Rail Pressure Sensor Circuit Low Input
The fuel rail pressure sensor circuit is reading too low — a signal voltage below the expected window. As the low-input counterpart to P0193, this usually points at a short to ground, an open or high-resistance connection, a failed sensor, or a genuine low-fuel-pressure condition. On direct-injection and diesel engines it can trigger reduced-power limp mode, so it's worth diagnosing promptly.
Read this codeFuel Rail Pressure Sensor Circuit High Input
The fuel rail pressure sensor's signal is pegged at the top of its range — usually a short to reference voltage or an open ground. This is the electrical mirror of P0192 (which sets when the signal pegs low) and a very different diagnosis from a real over-pressure condition (P0088).
Read this codeTurbocharger/Supercharger Overboost Condition
Boost pressure climbed higher than the PCM commanded and didn't come back down. On modern turbocharged engines, this is almost always a wastegate that won't open — not a damaged turbo, despite how it sounds.
Read this codeTurbocharger/Supercharger Boost Sensor "A" Circuit Low
The boost pressure sensor circuit is reading too low — a signal below the expected window. Despite the 'turbocharger' name, this is a sensor-circuit code: the usual causes are a short to ground, an open or corroded connection, a failed boost/MAP sensor, or a disconnected vacuum/pressure reference. It's worth fixing because the PCM uses boost pressure to manage the turbo, and a bad reading can trigger reduced-power mode.
Read this codeTurbocharger/Supercharger Underboost Condition
The PCM commanded boost, but the turbo can't deliver it. On Ford EcoBoost and VW/Audi TSI engines, this is one of the most-searched codes — and the cause is usually a boost leak somewhere in the charge piping or a tired wastegate actuator, not a dead turbo.
Read this codeRandom/Multiple Cylinder Misfire Detected
The engine computer detected misfires across multiple cylinders or random cylinders it can't isolate. The check engine light may be flashing, the engine may run rough, and continued driving can damage the catalytic converter.
Read this codeCylinder 1 Misfire Detected
The engine computer detected a misfire specifically in cylinder 1. Diagnosis is more targeted than P0300 — the bad part is on or feeding cylinder 1. The check engine light may be flashing; pull over if it is.
Read this codeCylinder 2 Misfire Detected
The engine computer detected a misfire specifically in cylinder 2. Diagnosis is more targeted than P0300 — the bad part is on or feeding cylinder 2. The check engine light may be flashing; pull over if it is.
Read this codeCylinder 3 Misfire Detected
The engine computer detected a misfire specifically in cylinder 3. Diagnosis is more targeted than P0300 — the bad part is on or feeding cylinder 3. The check engine light may be flashing; pull over if it is.
Read this codeCylinder 4 Misfire Detected
The engine computer detected a misfire specifically in cylinder 4. On a 4-cylinder engine, this is the last cylinder; on V engines, position varies by manufacturer. The check engine light may be flashing; pull over if it is.
Read this codeCylinder 5 Misfire Detected
The engine computer detected a misfire specifically in cylinder 5. This code only applies to engines with six or more cylinders. Diagnosis is more targeted than P0300 — the bad part is on or feeding cylinder 5.
Read this codeCylinder 6 Misfire Detected
The engine computer detected a misfire specifically in cylinder 6. This code only applies to engines with six or more cylinders. Diagnosis is more targeted than P0300 — the bad part is on or feeding cylinder 6.
Read this codeCylinder 7 Misfire Detected
Cylinder 7 is failing to fire cleanly on a measurable share of combustion events. Because only V8 (and a handful of V10/V12) engines have a cylinder 7, this code points you directly at a specific coil, plug, or injector on a known side of the engine.
Read this codeCylinder 8 Misfire Detected
Cylinder 8 — the last cylinder in the firing order on a V8 — is missing combustion events. The diagnosis is cylinder-specific, but cylinder 8 sits at the far back of a bank on most V8 platforms, which has real consequences for what the repair actually costs.
Read this codeMisfire Detected on Startup (First 1,000 Revolutions)
The PCM detected misfire activity during the first 1,000 revolutions after engine start — short enough that no single cylinder code set, but consistent enough to flag the startup window itself as a problem.
Read this codeKnock Sensor 1 Circuit (Bank 1 or Single Sensor)
The engine computer detected an electrical fault with the knock sensor. Without knock detection, the ECM pulls back ignition timing as a safety measure, which reduces power and hurts fuel economy. The engine still runs, but not at its best.
Read this codeKnock Sensor 1 Circuit Range/Performance (Bank 1 or Single Sensor)
The knock sensor on bank 1 is producing a signal, but it's out of the expected range — too weak, erratic, or not matching engine conditions. Unlike a flat circuit failure, a range/performance fault often points at an aging sensor, a loose mounting, or a contaminated connection. Because the PCM uses knock data to protect the engine, it may pull timing as a precaution, costing some power and economy.
Read this codeKnock Sensor 1 Circuit Low (Bank 1 or Single Sensor)
The knock sensor on bank 1 is reporting signal voltage below the PCM's minimum threshold — meaning the PCM is no longer hearing the engine. Without a working knock sensor, ignition timing defaults to a safer, more conservative map and the engine loses both power and efficiency.
Read this codeKnock Sensor 1 Circuit High (Bank 1 or Single Sensor)
The bank 1 knock sensor signal voltage is pinned at or near the upper threshold — usually because something has shorted the signal wire to the 5V reference, or the sensor itself has failed in a way that pegs its output high. Less common than P0327, and more often a wiring fault than a sensor fault.
Read this codeKnock Sensor 2 Circuit Malfunction (Bank 2)
The bank 2 knock sensor circuit has failed — the PCM is no longer hearing the engine on the side without cylinder 1. On V6 and V8 engines this means half of the engine is operating without knock protection, and the PCM defaults to conservative ignition timing across both banks.
Read this codeKnock Sensor 2 Circuit Low Input (Bank 2)
The second knock sensor — the one on bank 2 — is reporting signal voltage below the PCM's minimum threshold. If you've already read about P0327, this is the same failure on the opposite cylinder bank: the PCM has effectively gone deaf on that side and falls back to a conservative timing map.
Read this codeKnock Sensor 2 Circuit High Input (Bank 2)
The bank-2 knock sensor is reporting signal voltage above the PCM's maximum threshold — the opposite electrical fault from P0332. Where 'low input' usually means a short, 'high input' typically points to an open circuit: a broken wire, an unplugged connector, or a sensor that's gone open internally.
Read this codeCrankshaft Position Sensor "A" Circuit
The engine computer isn't getting a usable signal from the crankshaft position sensor. The engine may not start, may stall while driving, or may run intermittently — the crank sensor is critical for ignition and fuel injection timing.
Read this codeCrankshaft Position Sensor "A" Circuit Range/Performance
The crankshaft position sensor is producing a signal, but it's an implausible one — the pulse count, spacing, or amplitude doesn't match what the engine should be doing. Because the crank sensor is the master timing reference, a range/performance fault often shows up as intermittent stalling or hard starting, and the usual culprit is a damaged reluctor (tone) wheel or a sensor air-gap problem rather than a flat-dead circuit.
Read this codeCrankshaft Position Sensor "A" Circuit Low Input
The crankshaft position sensor circuit is reading too low — the voltage the PCM sees has fallen below the expected window, often pointing at a short to ground, an open circuit, or a failed sensor. Because the crank signal is the engine's primary timing reference, a low-input fault frequently means a no-start or stall, and the fix usually lives in the sensor, its connector, or the wiring rather than deep in the engine.
Read this codeCrankshaft Position Sensor "A" Circuit High Input
The crankshaft position sensor circuit is reading too high — the voltage the PCM sees has climbed above its expected window, which typically points at a short to voltage, a wiring fault, or a failed sensor. As the mirror image of the low-input code P0337, it carries the same stakes: because the crank signal is the engine's master timing reference, a high-input fault commonly means no-start or stalling.
Read this codeCamshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
The engine computer detected a circuit fault with the camshaft position sensor. The engine may hard-start, run rough, or refuse to start — the cam sensor tells the ECM which stroke each cylinder is on for fuel injection timing.
Read this codeCamshaft Position Sensor "A" Circuit Range/Performance
The camshaft position sensor is producing a signal, but it's not matching what the engine computer expects based on engine speed and crankshaft position. Often points to a stretched timing chain or a worn sensor.
Read this codeCamshaft Position Sensor "A" Circuit Low Input (Bank 1)
The camshaft position sensor circuit on bank 1 is reading too low — the voltage has dropped below its expected window, usually from a short to ground, an open circuit, or a failed sensor. Unlike a crank-sensor fault, many engines can still run on the crankshaft signal alone, so P0342 often shows up as a long crank, a stumble, or reduced power rather than a dead no-start.
Read this codeCamshaft Position Sensor "A" Circuit High Input (Bank 1)
The camshaft position sensor circuit on bank 1 is reading too high — the voltage has climbed above its expected window, usually from a short to voltage, a connector or wiring fault, or a failed sensor. As the mirror of the low-input code P0342, it carries the same milder consequences: because many engines run on the crank signal alone, you'll often see a hard start or stumble rather than a dead no-start.
Read this codeCamshaft Position Sensor "A" Circuit Intermittent (Bank 1)
The bank-1 camshaft position sensor signal is cutting in and out. The defining trait is 'intermittent' — it works most of the time, then briefly drops or glitches before recovering. That makes it the trickiest of the cam-sensor codes to pin down, because the fault is often gone by the time you test, and the usual culprits are a loose connector, a chafed wire, or oil intrusion rather than a flat-dead sensor.
Read this codeEGR Insufficient Flow Detected
The engine computer commanded the exhaust gas recirculation (EGR) valve to open, but the resulting flow was lower than expected. Almost always caused by carbon buildup clogging the EGR passages or a stuck-closed EGR valve.
Read this codeExhaust Gas Recirculation Flow Excessive Detected
The PCM is detecting more EGR flow into the intake than it commanded — usually because carbon buildup has the EGR valve stuck partially open, or the valve seat itself has eroded enough that it can't fully close. This is the mirror of P0401 (insufficient flow), and it's almost always a mechanical EGR cleaning or replacement job.
Read this codeExhaust Gas Recirculation Control Circuit Malfunction
The PCM is detecting a fault in the electrical circuit that drives the EGR valve — not the valve itself, but the wiring, connector, or driver that commands it open and closed. If P0402 is about the valve being mechanically stuck, P0403 is about the electrical side losing its connection to the valve.
Read this codeExhaust Gas Recirculation Control Circuit Range/Performance
The EGR valve is responding to commands, but not the way the PCM expects. The diagnostic question is: is the valve mechanically sticky from carbon, or is the position sensor inside the valve drifting and reporting positions that don't match reality?
Read this codeExhaust Gas Recirculation Sensor 'A' Circuit Low
The EGR valve's position feedback signal is reading too low — pinned near zero volts. This is the position-sensor side of the EGR family, distinct from valve-side mechanical failures: the valve may be moving correctly, but the sensor reporting its position has dropped out.
Read this codeExhaust Gas Recirculation Sensor 'A' Circuit High
The EGR position-feedback signal is reading too high — pinned near the top of its range. This is the high-side mirror of P0405: the valve may be moving correctly, but the 'A' sensor reporting its position has gone open or shorted high, so the PCM no longer trusts the feedback.
Read this codeExhaust Gas Recirculation Sensor 'B' Circuit Low
The EGR 'B' feedback signal is reading too low. On the platforms where this code matters most, Sensor B is a dedicated EGR gas temperature sensor rather than a valve position channel — which is why the primary fix here is the temperature sensor, not the valve.
Read this codeExhaust Gas Recirculation Sensor 'B' Circuit High
The EGR 'B' feedback signal is reading too high — the opposite electrical fault from P0407. On a temperature-sensor design, high voltage reads as impossibly cold and almost always means an open circuit: a broken wire, a disconnected connector, or a sensor that's failed open.
Read this codeSecondary Air Injection System Malfunction
The secondary air injection system (which briefly pumps fresh air into the exhaust on cold start to warm the catalyst) is not working as expected. Common on European cars and certain GM models — often a failed air pump, and frequently expensive.
Read this codeSecondary Air Injection System Incorrect Flow Detected
The secondary air injection system (which briefly pumps fresh air into the exhaust during cold start to help warm up the catalyst) is not flowing the expected amount of air. Common on European cars and certain GM models — and often expensive to fix.
Read this codeSecondary Air Injection System Switching Valve A Circuit Malfunction
The engine computer detected a fault in the control circuit for the secondary air switching valve — the valve that routes pumped air into the exhaust on cold start. Often a failed solenoid, stuck valve, or wiring fault.
Read this codeSecondary Air Injection System Switching Valve A Circuit Open
The engine computer detected an open electrical circuit to the secondary air switching valve A — the wiring or connector is broken, or the solenoid has failed open. The pumped cold-start air can't be routed into the exhaust.
Read this codeSecondary Air Injection System Switching Valve A Circuit Shorted
The engine computer detected a short in the secondary air switching valve A circuit — the wiring is shorted to ground or power, or the solenoid has failed internally. The pumped cold-start air can't be routed into the exhaust.
Read this codeSecondary Air Injection System Relay A Circuit Malfunction
The engine computer detected an electrical fault in the relay that powers the secondary air injection pump. The pump can't be energized to push cold-start air into the exhaust, so the check engine light is on — but the car still drives normally.
Read this codeCatalyst System Efficiency Below Threshold (Bank 1)
The engine computer detected that the catalytic converter on Bank 1 is not reducing emissions as efficiently as expected. The check engine light is on, but the car is usually still drivable.
Read this codeWarm Up Catalyst Efficiency Below Threshold (Bank 1)
The warm-up catalyst on bank 1 — the small cat mounted close to the engine for fast cold-start emissions control — isn't converting pollutants efficiently anymore. Bank 1 contains cylinder 1, so on most American engines this is the driver-side cat.
Read this codeMain Catalyst Efficiency Below Threshold (Bank 1)
The PCM has decided the main catalytic converter on bank 1 isn't cleaning the exhaust well enough. It's a close relative of the far more common P0420 — same monitor, same two-sensor logic — but the wording points specifically at the main catalyst brick. The honest reality is that a worn converter is the usual answer, but it's worth ruling out a lazy downstream O2 sensor and exhaust leaks first, because those are far cheaper.
Read this codeHeated Catalyst Efficiency Below Threshold (Bank 1)
The efficiency monitor for the heated catalyst on bank 1 has fallen below its threshold. This one is worth understanding before you spend money: it specifically refers to a heated-catalyst design, so on many vehicles the real story is the same converter-efficiency logic as P0420 — but on cars that actually use an electrically heated catalyst, the heater circuit itself can be part of the problem.
Read this codeCatalyst System Efficiency Below Threshold (Bank 2)
The engine computer detected that the catalytic converter on Bank 2 is not reducing emissions as efficiently as expected. Same condition as P0420, but for the opposite side of a V-configured engine. The check engine light is on, but the car is usually still drivable.
Read this codeWarm Up Catalyst Efficiency Below Threshold (Bank 2)
The warm-up catalyst on bank 2 — the smaller cat mounted close to the engine for fast light-off during cold starts — isn't reducing emissions efficiently enough. Different from the main cat code (P0420/P0430) in location and failure pattern.
Read this codeCatalyst System Efficiency Below Threshold (Bank 2)
The main catalytic converter on bank 2 has lost enough efficiency that the PCM no longer trusts it to handle the emissions load. Same problem as the widely-searched P0420, just on the opposite side of the engine.
Read this codeHeated Catalyst Efficiency Below Threshold (Bank 2)
This is the bank-2 twin of P0423 — the heated-catalyst efficiency monitor has dropped below threshold, but on the cylinder bank opposite the engine's number-one cylinder. The single most useful thing to know is that 'bank 2' tells you exactly where to look, and that comparing both banks often reveals whether you have a real converter problem or a misleading sensor.
Read this codeEvaporative Emission Control System Malfunction
A general code indicating a problem with the evaporative emission (EVAP) system. Most often a loose gas cap, a cracked hose, or a faulty purge or vent valve. The car drives normally but will fail an emissions test.
Read this codeEVAP System Incorrect Purge Flow
The EVAP purge system is moving fuel vapor at the wrong rate — too much, too little, or at the wrong time relative to what the PCM commanded. Different from the 'leak' codes (P0440, P0455, P0456) — this one is about flow direction and quantity, not whether the system holds pressure.
Read this codeEvaporative Emission System — Small Leak Detected
The engine computer detected a small leak in the evaporative emission (EVAP) system. The check engine light is on but the car runs normally. The most common cause is a worn gas cap or a small crack in an EVAP hose.
Read this codeEvaporative Emission System Vent Control Circuit Malfunction
The vent valve in the evaporative emission (EVAP) system has an electrical or mechanical fault. Often caused by a failed vent solenoid or by debris and spider webs clogging the vent — both inexpensive fixes.
Read this codeEvaporative Emission System Vent Control Circuit Open
The engine computer detected an open electrical circuit to the EVAP canister vent valve — the wiring or connector is broken, or the vent solenoid itself has failed open. Usually an inexpensive fix once the open is located.
Read this codeEvaporative Emission System Vent Control Circuit Shorted
The engine computer detected a short in the EVAP canister vent valve circuit — the wiring is shorted to ground or power, or the solenoid has failed internally. Usually an inexpensive fix once the short is located.
Read this codeEVAP Vent Solenoid Control Circuit Malfunction
An electrical fault in the circuit that controls the EVAP vent solenoid — the valve that seals the system closed during leak testing. Different from P0446, which is a performance fault; P0449 is specifically about the wiring or solenoid windings.
Read this codeEvaporative Emission System — Large Leak Detected
The engine computer detected a large leak in the evaporative emission (EVAP) system. The most common cause is a loose, missing, or damaged gas cap. The car runs normally but will fail an emissions test until the leak is fixed.
Read this codeEVAP System Very Small Leak Detected
The EVAP system has a leak roughly 0.020 inches in diameter — about half the size of P0455's threshold. About 50% of these codes turn out to be the gas cap. The rest can be frustrating to find because the leak is tiny.
Read this codeEvaporative Emission System Leak Detected (Fuel Cap Loose/Off)
The engine computer detected an EVAP leak and specifically identified the fuel cap as the suspected location. Almost always solved by tightening or replacing the gas cap — the cheapest fix in the EVAP family.
Read this codeCooling Fan Relay 1 Control Circuit
The PCM has detected an electrical fault in the control circuit for the primary cooling fan relay — usually a failed relay, damaged wiring, or a problem with the fan motor itself.
Read this codeCooling Fan 2 Control Circuit
The engine computer detected an electrical fault in the control circuit for the secondary (fan 2) cooling fan or its relay. The car still drives, but the cooling system has lost part of its capacity, so overheating is a real risk in traffic.
Read this codeCooling Fan 3 Control Circuit
The engine computer detected an electrical fault in the control circuit for a third cooling fan or fan-control stage. The car drives normally, but the cooling system has lost capacity, so overheating becomes a risk in heavy demand.
Read this codeCooling Fan Rationality Check Failed
The engine computer ran a logic check on the cooling fan system and the results didn't add up — the fan's actual behavior doesn't match what the PCM commanded or expected from coolant temperature. The car drives, but the cooling system may not be working correctly.
Read this codeExhaust Gas Recirculation Throttle Position Control Range/Performance
The EGR throttle — an intake throttle plate used to help drive exhaust-gas recirculation flow — isn't moving to the position the PCM commands. Common on diesels and some EGR-heavy gasoline engines, this is usually a carbon-fouled or sticking EGR throttle, an actuator or motor fault, or a wiring/sensor problem. Expect reduced EGR performance, possible limp mode, and a failed emissions test until it's resolved.
Read this codeEvaporative Emission System Flow During Non-Purge Condition
The EVAP system is showing fuel vapor flow when the PCM hasn't commanded the purge valve open — almost always a stuck-open or leaking purge valve letting vapor pass into the engine continuously instead of only during scheduled purge events.
Read this codeVehicle Speed Sensor 'A' Malfunction
The powertrain control module isn't getting a usable vehicle-speed signal. On older vehicles that means a failed vehicle speed sensor; on most newer ones, where speed is calculated from the ABS wheel-speed sensors, it often points to a wheel-speed sensor or wiring instead.
Read this codeVehicle Speed Sensor 'A' Range / Performance
The vehicle-speed signal is present but doesn't make sense — it's erratic, drops in and out, or disagrees with what the other sensors say the car is doing. Where P0500 means no signal, P0501 means a signal the PCM can see but can't trust.
Read this codeVehicle Speed Sensor 'A' Circuit Low Input
The vehicle-speed signal is reading persistently low — below what the PCM expects when the car is clearly moving. Where P0500 means no signal at all, P0502 means a weak, suppressed signal that usually points to a short to ground, a dragging sensor, or a high-resistance connection.
Read this codeVehicle Speed Sensor 'A' Intermittent / Erratic / High
The vehicle-speed signal is jumping around, spiking high, or cutting in and out — present one moment and wrong the next. This is the intermittent member of the speed-sensor family, and intermittent faults are the hardest to pin down because they often vanish the moment you go looking.
Read this codeIdle Air Control System Malfunction
The idle air control (IAC) valve isn't responding to PCM commands the way it should — idle is rough, hunting, stalling, or running too high. Applies to older pre-electronic-throttle vehicles where a dedicated IAC valve controls idle airflow around a mechanically-cabled throttle.
Read this codeIdle Air Control System RPM Lower Than Expected
The engine is idling slower than the PCM's target RPM and the idle control strategy can't bring it back up — usually a dirty throttle body, a tired idle air control valve, or a vacuum-related restriction.
Read this codeIdle Air Control System RPM Higher Than Expected
The engine is idling faster than the PCM's target RPM and the idle control strategy can't bring it back down — most often a vacuum leak letting extra air past the throttle plate.
Read this codeEngine Oil Pressure Sensor/Switch Circuit Malfunction
The catch-all circuit fault for the oil pressure sensor — the PCM has detected a general problem with the sensor circuit that doesn't land cleanly in the low (P0522) or high (P0523) bucket. As with the rest of this family, the fix is usually a cheap sensor, but the discipline of verifying real pressure first is non-negotiable.
Read this codeEngine Oil Pressure Sensor/Switch Range/Performance
The PCM is seeing an oil pressure value that doesn't match what it expects for the current RPM, temperature, and load — but it's not pegged at zero or maxed out. The question every P0521 diagnosis has to answer first: is the engine actually low on oil pressure, or is the sensor lying?
Read this codeEngine Oil Pressure Sensor/Switch Low Voltage
The PCM is seeing the oil pressure sensor signal pinned at or near zero volts. On GM Vortec V8 trucks this is one of the most-searched codes in existence — and the gauge dropping to zero in the dash is what brings people in. The fix is almost always a $40 sensor.
Read this codeEngine Oil Pressure Sensor/Switch High Voltage
The PCM is seeing the oil pressure sensor signal pinned at or near the 5V reference. This is almost never real oil pressure — it's the inverse of P0522, and it usually catches DIYers off-guard because the dash gauge may be reading abnormally high or maxed out.
Read this codeEngine Oil Pressure Too Low
Unlike the rest of this family, P0524 is not a circuit code — it's the PCM declaring that measured oil pressure is genuinely below what the engine needs. Treat it as a real low-pressure event until a mechanical gauge proves otherwise, and do not keep driving on it.
Read this codeCooling Fan Speed Sensor Circuit
The engine computer isn't getting a valid speed signal back from the cooling fan. On vehicles with variable-speed or PWM-controlled fans, the PCM expects to see how fast the fan is actually spinning, and that feedback is missing or out of range.
Read this codeSystem Voltage Low
The PCM is seeing battery voltage below the threshold needed for normal operation — usually a failing alternator, an aging battery, or a poor connection on the main charging circuit.
Read this codeSystem Voltage High
The PCM is seeing battery voltage above the maximum safe operating range — almost always a failed voltage regulator inside the alternator pushing too much charge into the system.
Read this codeSerial Communication Link Malfunction
The powertrain control module lost communication over one of the serial data links it uses to talk to other modules or internal processors. It's a network/communication fault rather than a sensor problem — wiring, connectors, grounds, and power supply are the usual culprits before the PCM itself.
Read this codeInternal Control Module Memory Checksum Error
The powertrain control module ran a self-check on its own memory and the checksum didn't match what it expected — the data the computer relies on may be corrupted. Often a software/programming issue resolvable with a reflash, sometimes a genuine internal PCM failure.
Read this codeControl Module Programming Error
The powertrain control module detected that its programming or calibration is missing, incomplete, or not correctly loaded. It almost always points to a software/flashing problem rather than a failed sensor — and is frequently fixable by reprogramming the module with the correct calibration.
Read this codeInternal Control Module Keep Alive Memory (KAM) Error
The PCM's Keep Alive Memory — the data it retains between key cycles, like learned fuel trims and idle settings — failed its self-check. Very often caused by a weak battery, a bad ground, or a recently disconnected battery, and frequently fixed with a simple power-side repair.
Read this codeInternal Control Module Random Access Memory (RAM) Error
The PCM detected a fault in its internal RAM — the working memory it uses for live calculations while the engine runs. Unlike the learned-data codes, this points more strongly at the module hardware itself, though power and ground problems should be ruled out first.
Read this codeInternal Control Module Read Only Memory (ROM) Error
The PCM failed a self-check on its Read Only Memory — the permanent storage that holds the program and calibration the computer runs from. ROM faults point strongly at the module hardware or its software image, and usually mean a reflash or a module replacement.
Read this codePCM Processor Fault
The powertrain control module has detected an internal processor or memory fault — the computer that runs your engine has flagged a problem with itself. Rare across most platforms, but unusually common on certain Ford EcoBoost and Chrysler V6 engines where the cause is often a known PCM hardware defect.
Read this codeControl Module Performance
The PCM detected that its internal processor isn't performing as expected — a self-monitoring or rationality check inside the computer failed. It's a broad internal-fault code; power and ground problems are checked first, but it often ends in a reflash or module replacement.
Read this codeGenerator Control Circuit Malfunction
The PCM has detected a fault in the circuit it uses to control the alternator (generator). On modern vehicles the computer regulates charging output, and P0620 means that command-and-feedback link isn't behaving — often a wiring or connector problem, a failing alternator regulator, or the alternator itself. Left unfixed it can mean over- or under-charging, so it's worth diagnosing before the battery pays the price.
Read this codeGenerator Lamp "L" Control Circuit Malfunction
The PCM has flagged a fault in the alternator's "L" (lamp) terminal circuit — the wire tied to the charging warning light and the alternator's turn-on signal. Often this is a wiring or connector issue or a failing alternator regulator rather than a catastrophic charging failure, but because the L terminal both signals charging status and helps excite the alternator, it's worth checking before the battery light becomes a dead battery.
Read this codeGenerator Field "F" Control Circuit Malfunction
The PCM has detected a fault in the alternator's "F" (field) control circuit — the circuit that actually regulates how hard the alternator charges by controlling its field/rotor winding. Because the field circuit is the lever the computer pulls to set charging output, a fault here often shows up as under- or over-charging, and the cause is usually wiring, the alternator's internal regulator, or the alternator itself.
Read this codeGenerator Field/F Terminal Circuit Low
The voltage on the alternator's field (F) terminal circuit is reading too low. As the low-voltage member of the generator field-control family, P0625 usually points at a short to ground, an open or high-resistance connection, or a failing alternator regulator. Because the field terminal sets charging output, a low reading here can mean the alternator isn't being driven to charge properly.
Read this codeGenerator Field/F Terminal Circuit High
The voltage on the alternator's field (F) terminal circuit is reading too high — the mirror image of P0625's low condition. As the high-side member of the generator field-control family, P0626 usually points at a short to voltage, a wiring or connector fault, or a failing alternator regulator. Because the field terminal sets charging output, a high reading can coincide with over-charging, which stresses the battery.
Read this codeCooling Fan 1 Control Circuit Low
The engine computer detected low voltage on the control circuit for the primary cooling fan relay — the circuit is reading near ground when it shouldn't be, pointing to a short to ground or a failed relay. Overheating in traffic is the main risk.
Read this codeCooling Fan 1 Control Circuit High
The engine computer detected high voltage — or an open circuit — on the control circuit for the primary cooling fan relay. The PCM expected the circuit to pull low and it didn't, pointing to an open wire, a failed relay, or a bad connection. Overheating in slow traffic is the main risk.
Read this codeEngine Oil Pressure Control Circuit Stuck Off
On engines with a variable or two-stage oil pump, the PCM commands oil pressure through a control solenoid — and P06DD means that control circuit is stuck in the off/low state and won't switch to the commanded pressure. The usual causes are the oil pressure control solenoid, its wiring or connector, or sludge holding the valve. Because oil pressure feeds lubrication and variable valve timing, it's worth verifying real pressure promptly.
Read this codeTransmission Control System Malfunction
An umbrella code indicating the transmission control module has detected a fault. The transmission may be in limp mode. Drive directly to a repair shop — the underlying transmission code (often P0741 or a P0750-series code) is what tells the real story.
Read this codeInput / Turbine Speed Sensor Circuit Malfunction
The transmission's input (turbine) speed sensor is reporting an erratic, missing, or impossible signal. This is the sensor that tells the transmission control module how fast the input shaft is spinning after the torque converter — the counterpart to the output speed sensor in P0720.
Read this codeInput / Turbine Speed Sensor Circuit Range/Performance
The input (turbine) speed sensor is sending a signal, but it's an implausible one — present yet wrong, jumpy, or not matching what engine RPM and gear say it should be. Unlike a flat-out no-signal fault, a range/performance code means the PCM is getting data it doesn't believe, which often points at sensor air-gap, reluctor, or fluid issues rather than a dead circuit.
Read this codeInput / Turbine Speed Sensor No Signal
The input (turbine) speed sensor circuit is producing no signal at all while the transmission is clearly turning. Where P0715 covers an erratic or out-of-range reading, P0717 is the total-dropout case — the TCM sees nothing where it should see shaft speed.
Read this codeInput / Turbine Speed Sensor Circuit Intermittent
The input (turbine) speed sensor signal is cutting in and out. The defining word here is 'intermittent' — the sensor works most of the time, then briefly drops out or glitches before recovering. That on-again-off-again behavior makes this the trickiest of the input-speed-sensor codes, because the fault is often gone by the time you go looking for it.
Read this codeOutput Speed Sensor Circuit Malfunction
The transmission's output speed sensor is reporting an erratic, missing, or impossible signal. This is the sensor the transmission control module uses to know how fast the output shaft is spinning — without it, the TCM can't shift correctly or know what gear to be in.
Read this codeOutput Speed Sensor Circuit Range/Performance
The output speed sensor — the one that measures how fast power is leaving the transmission toward the wheels — is sending a reading the PCM doesn't believe. It's present but out of range or out of step with vehicle speed and wheel data. Because output speed also feeds the speedometer and ABS on many vehicles, this code can come with a glitchy speedo as a telltale clue.
Read this codeOutput Speed Sensor Circuit No Signal
The transmission is getting no signal at all from the output speed sensor — the reading has gone to zero or flatlined while the car is clearly moving. This is the most clear-cut of the output-speed codes: not a wrong value, but nothing. Expect a dead or frozen speedometer, a transmission that often falls straight into limp mode, and a fault that's usually a broken circuit or failed sensor rather than a subtle calibration issue.
Read this codeGear 1 Incorrect Ratio
The transmission's actual gear ratio in first gear doesn't match what it should be — the PCM compares input and output shaft speeds and sees the wrong relationship. P0731 usually points at internal slipping (worn clutches or bands), low or degraded fluid, a shift solenoid or valve-body problem, or a speed-sensor issue. It often comes with slipping, harsh shifts, or a drop into limp mode, and warrants prompt attention to avoid further transmission damage.
Read this codeTorque Converter Clutch Circuit Malfunction / Open
The PCM has found an electrical problem in the torque converter clutch solenoid circuit — usually an open or shorted winding, a bad connector, or damaged wiring. Where P0741 means the clutch isn't locking (a performance fault), P0740 means the circuit that commands it has an electrical fault.
Read this codeTorque Converter Clutch Circuit Performance / Stuck Off
The torque converter clutch isn't locking up when the PCM commands it to — usually a worn TCC solenoid, dirty transmission fluid, or internal wear inside the converter itself.
Read this codeTorque Converter Clutch Circuit Stuck On
The torque converter clutch is staying locked when it should release. The classic giveaway is the engine stalling as you come to a stop — like a manual-transmission car you forgot to declutch — because the engine and transmission can't decouple at idle.
Read this codeTorque Converter Clutch Circuit Electrical
An electrical fault has been confirmed in the torque converter clutch solenoid circuit — typically an open or shorted solenoid winding, a damaged connector, or a wiring fault. It's the explicitly electrical sibling of P0740, and on many vehicles the two are nearly interchangeable.
Read this codeTorque Converter Clutch Circuit Intermittent
The torque converter clutch circuit is faulting intermittently — locking and unlocking erratically, or throwing a fault that comes and goes. Like all intermittent codes, it's the hardest of the TCC family to catch because the problem often isn't present when you go looking for it.
Read this codeShift Solenoid A Malfunction
An electrical or hydraulic fault has been detected in shift solenoid A, the solenoid that controls one of the lower gear shifts on most automatic transmissions.
Read this codeShift Solenoid "A" Performance or Stuck Off
Shift solenoid A is responding to commands electrically, but it isn't doing its hydraulic job — it's stuck off or performing poorly, so a gear doesn't engage when the transmission asks for it. Unlike the electrical code P0753, this is usually a mechanical or hydraulic problem: a stuck valve, varnish, low or dirty fluid, or debris, which is why a fluid service is the cheapest first move.
Read this codeShift Solenoid "A" Electrical
This is the electrical-fault counterpart to P0751: shift solenoid A's circuit has an open, short, or out-of-range resistance, so the TCM can't drive the solenoid properly. Because the problem is electrical rather than hydraulic, the productive checks are the solenoid's coil resistance, the wiring, and the connector — and a surprising share of these trace to the transmission's internal harness or external connector rather than the solenoid itself.
Read this codeShift Solenoid "B" Malfunction
Shift solenoid B has a fault — electrical, hydraulic, or both. The useful thing to understand is that shift solenoids work in combination: the TCM energizes A, B, and sometimes C in specific on/off patterns to select each gear, so a failed B knocks out the gears that depend on it. That's why P0755 often shows up as the transmission missing or being stuck out of a particular set of gears rather than failing entirely.
Read this codeShift Solenoid "C" Malfunction
Shift solenoid C has a fault — electrical or hydraulic. Solenoid C is the third member of the shift-solenoid set, used on transmissions with enough gears to need a third element in the on/off combination. Losing it typically affects the higher gears or overdrive that depend on C, so P0760 often surfaces as a transmission that won't reach top gear or that shifts harshly in the upper range.
Read this codePost Catalyst Fuel Trim System Too Lean (Bank 1)
The downstream oxygen sensor on bank 1 is reporting a persistently lean signal that the PCM can't correct for, even after the upstream fuel trim has done its work. This points at exhaust leaks, sensor problems, or a cat that's letting unburned oxygen pass through.
Read this codePost Catalyst Fuel Trim System Too Rich (Bank 1)
The bank 1 downstream oxygen sensor is reporting a persistently rich signal that the PCM can't correct out. Usually means a contaminated downstream sensor, a cat that's saturated and dumping unburned fuel through, or fuel system issues that don't trip the upstream lean/rich codes.
Read this codePost Catalyst Fuel Trim System Too Lean (Bank 2)
The downstream oxygen sensor on bank 2 is reporting a persistently lean signal. Mechanically identical to P2096 — same diagnosis, same costs — but you're chasing it on the side of the engine that does NOT contain cylinder 1. Bank identification is the first step.
Read this codePost Catalyst Fuel Trim System Too Rich (Bank 2)
The downstream O2 sensor on bank 2 is reporting a persistently rich signal. Same playbook as P2097 — contaminated sensor, leaking injector, stuck EVAP, or fuel pressure issue — but on the side of the engine that doesn't contain cylinder 1.
Read this codeThrottle/Pedal Position Sensor 'D' Circuit Low Input
One of the two sensors inside the accelerator pedal assembly is reporting near-zero voltage no matter where the pedal is. Different from P0122 — this code is about the pedal side of the drive-by-wire system, not the throttle body.
Read this codeThrottle/Pedal Position Sensor 'D' Circuit High Input
The 'D' accelerator pedal position sensor is reading too high — a signal voltage above its expected window. As the high-input mirror of P2122, it usually traces to a short to voltage, a connector or wiring fault, or a failed pedal sensor. Because drive-by-wire systems treat pedal signals as safety-critical, this often comes with reduced-power limp mode until it's resolved.
Read this codeThrottle/Pedal Position Sensor 'E' Circuit Low Input
The 'E' position sensor inside the accelerator pedal assembly — the second of the two redundant sensors — is reporting near-zero voltage no matter where the pedal is. Paired sibling of P2122 but on the redundant sensor circuit.
Read this codeThrottle/Pedal Position Sensor 'E' Circuit High Input
The 'E' accelerator pedal position sensor is reading too high — a signal voltage above its expected window. As the high-input mirror of P2127, and the companion to the 'D'-channel code P2123, it usually traces to a short to voltage, a connector or wiring fault, or a failed pedal sensor. Drive-by-wire systems treat pedal signals as safety-critical, so reduced-power limp mode is common until it's fixed.
Read this codeThrottle/Pedal Position Sensor 'A'/'B' Voltage Correlation
The two throttle position sensors inside the throttle body don't agree with each other. On GM trucks and SUVs in particular this is THE 'Reduced Engine Power' code that strands owners on the shoulder — and the first thing to try is often a $10 can of throttle body cleaner.
Read this codeThrottle/Pedal Position Sensor 'D'/'E' Voltage Correlation
The two sensors inside the accelerator pedal don't agree with each other. Pedal-side mirror of P2135 — same correlation logic, but the failure is in the pedal under the dash, not in the throttle body. No cleaning will fix this one.
Read this codeTurbocharger/Supercharger Boost System Performance
The boost system isn't delivering the pressure the PCM expects — a performance fault rather than a single circuit fault. P2263 means measured boost doesn't match the target, which on a turbo engine usually traces to a boost leak, a sticking or failing wastegate or variable-vane mechanism, oil-related turbo problems, or a restriction. Expect reduced power and sluggish acceleration until it's resolved.
Read this codeExhaust Gas Recirculation System Performance
The EGR system isn't performing the way the PCM expects — actual exhaust-gas recirculation doesn't match the commanded amount. It's a performance code rather than a single circuit fault, and the overwhelmingly common cause is carbon: clogged EGR passages, a sticking valve, or a fouled cooler. Cleaning or replacing the EGR valve and clearing the passages is the usual fix.
Read this codeNetwork & vehicle communication (U codes)
233 codes published.
High Speed CAN Communication Bus
A general fault on the vehicle's high-speed CAN communication bus — the backbone network that lets modules talk to each other. Usually a wiring, connector, or single-module fault that disrupts the whole network.
Read this codeHigh Speed CAN Communication Bus (Performance)
The high-speed CAN bus is communicating, but not reliably — messages are corrupted, delayed, or intermittent. Often a harder-to-find version of a full bus failure, frequently caused by marginal wiring or a flaky module.
Read this codeHigh Speed CAN Communication Bus (+) Open
The CAN-High (positive) wire of the high-speed communication bus is open — broken, disconnected, or interrupted somewhere in the harness. Modules lose the ability to talk to one another over that line.
Read this codeHigh Speed CAN Communication Bus (+) Low
The CAN-High (positive) line of the high-speed bus is reading too low — usually a short to ground or a bias problem dragging the positive signal down. Communication across the network degrades or fails.
Read this codeHigh Speed CAN Communication Bus (+) High
The CAN-High (positive) line of the high-speed bus is reading too high — usually shorted to battery or another voltage source. The elevated voltage corrupts the differential signal and disrupts the network.
Read this codeHigh Speed CAN Communication Bus (-) Open
The CAN-Low (negative) wire of the high-speed communication bus is open — broken, disconnected, or interrupted in the harness. Modules downstream of the break can no longer exchange data.
Read this codeHigh Speed CAN Communication Bus (-) Low
The CAN-Low (negative) line of the high-speed bus is reading too low — usually shorted to ground or dragged down. The collapsed differential disrupts communication across the network.
Read this codeHigh Speed CAN Communication Bus (-) High
The CAN-Low (negative) line of the high-speed bus is reading too high — usually shorted to a power source or to CAN-High. The elevated voltage corrupts the differential and disrupts the network.
Read this codeHigh Speed CAN Communication Bus (-) Shorted to Bus (+)
The two high-speed CAN wires — CAN-Low and CAN-High — are shorted together. This collapses the bus voltage and disrupts communication for nearly every module on the network. Usually a wiring or connector fault.
Read this codeMedium Speed CAN Communication Bus
A general fault on the vehicle's medium-speed CAN bus — the slower network that typically links body, comfort, and convenience modules. Usually a wiring, connector, or single-module fault on that bus.
Read this codeMedium Speed CAN Communication Bus (Performance)
The medium-speed CAN bus is communicating, but not reliably — messages are corrupted, intermittent, or out of spec. A 'performance' fault points to a degrading network rather than a fully dead one.
Read this codeMedium Speed CAN Communication Bus (+) Open
The positive (CAN-High) wire of the medium-speed communication bus has an open — a break, loose pin, or disconnected segment. Modules on that bus can no longer exchange messages reliably.
Read this codeMedium Speed CAN Communication Bus (+) Low
The positive (CAN-High) wire of the medium-speed communication bus is reading too low — usually shorted to ground or dragged down. The weakened differential disrupts messages between body and comfort modules.
Read this codeMedium Speed CAN Communication Bus (+) High
The positive (CAN-High) wire of the medium-speed communication bus is reading too high — usually shorted to a voltage source or pulled up. The distorted signal disrupts messages between body and comfort modules.
Read this codeMedium Speed CAN Communication Bus (-) Open
The negative (CAN-Low) wire of the medium-speed communication bus has an open — a break, loose pin, or disconnected segment. Modules on that bus can no longer exchange messages reliably.
Read this codeMedium Speed CAN Communication Bus (-) Low
The negative (CAN-Low) wire of the medium-speed communication bus is reading too low — usually shorted to ground or dragged down. The weakened differential disrupts messages between body and comfort modules.
Read this codeMedium Speed CAN Communication Bus (-) High
The negative (CAN-Low) wire of the medium-speed communication bus is reading too high — usually shorted to a voltage source or pulled up. The distorted signal disrupts messages between body and comfort modules.
Read this codeMedium Speed CAN Communication Bus (-) shorted to Bus (+)
The negative (CAN-Low) wire of the medium-speed bus is shorted to the positive (CAN-High) wire. With the two lines tied together the voltage difference collapses and modules on that bus can no longer communicate.
Read this codeLow Speed CAN Communication Bus
A general fault on the vehicle's low-speed CAN bus — the slowest network, used for low-priority comfort and convenience features. Usually a wiring, connector, or single-module fault on that bus.
Read this codeVehicle Communication Bus B
A general fault on the vehicle's second communication bus (Bus B) — a secondary CAN network used by modules that aren't on the main high-speed powertrain bus. Usually a wiring, connector, or single-module fault that disrupts that bus.
Read this codeVehicle Communication Bus B (Performance)
The vehicle's second communication bus (Bus B) is up, but not reliable — messages are corrupted, delayed, or intermittent. Often a harder-to-find version of a full bus failure, frequently caused by marginal wiring or a flaky module.
Read this codeControl Module Communication Bus A Off
A control module has counted so many communication errors that it shut itself off the CAN bus to protect the network — the 'bus off' state. Almost always a wiring short or a failed module transceiver.
Read this codeControl Module Communication Bus B Off
A control module counted so many communication errors on the second bus (Bus B) that it shut itself off the network — the 'bus off' state. Almost always a wiring short or a failed module transceiver on that bus.
Read this codeControl Module Communication Bus C
A general fault on the vehicle's third communication bus (Bus C) — an additional CAN or sub-network used by modules separated from the main and second buses. Usually a wiring, connector, or single-module fault on that bus.
Read this codeLost Communication with ECM/PCM
Another module on the vehicle's communication network has lost contact with the engine control module. Almost always a wiring, power, or ground issue — and frequently a no-start condition.
Read this codeLost Communication with TCM (Transmission Control Module)
A module on the network can no longer hear from the transmission control module. Often a power, ground, or wiring fault at the TCM — and frequently the transmission drops into limp mode.
Read this codeLost Communication with Transfer Case Control Module
A module on the network can no longer hear from the transfer case control module. Usually a power, ground, or wiring fault — and because this module manages four-wheel and all-wheel drive, the vehicle may lose 4WD/AWD function or default to a single drive mode.
Read this codeLost Communication with Gear Shift Module
A module on the network can no longer hear from the gear shift module — the shift-by-wire gear selector controller. Often a power, ground, or wiring fault, and on shift-by-wire vehicles the transmission may refuse to change gears or default to a fail-safe.
Read this codeLost Communication with Cruise Control Module
A module on the network can no longer hear from the cruise control module. Usually a power, ground, or wiring fault — and on vehicles with adaptive cruise control, the radar-based following and speed features go offline along with conventional cruise.
Read this codeLost Communication with Fuel Injector Control Module
A module on the network can no longer hear from the fuel injector control module. Usually a power, ground, or wiring fault — and because this module drives the injectors, the engine may misfire, run rough, lose power, or fail to start.
Read this codeLost Communication with Glow Plug Control Module
A module on the network can no longer hear from the glow plug control module. Usually a power, ground, or wiring fault — and because this diesel module preheats the cylinders, you may get hard cold starts, rough cold running, and white startup smoke.
Read this codeLost Communication with Throttle Actuator Control Module
A module on the network can no longer hear from the throttle actuator control module. Usually a power, ground, or wiring fault — and because this module runs the electronic throttle, the engine often drops into reduced-power limp mode or won't respond to the pedal.
Read this codeLost Communication with Fuel Pump Control Module
A module on the network can no longer hear from the fuel pump control module. Often a power, ground, or wiring fault — and because the module regulates fuel delivery, the engine may run poorly, stall, or fail to start.
Read this codeLost Communication with Drive Motor Control Module
A module on the network can no longer hear from the drive motor control module. Usually a power, ground, or wiring fault — and because this module runs the electric traction motor, a hybrid or EV may lose propulsion, cut power, or refuse to move.
Read this codeLost Communication with Battery Energy Control Module A
A module on the network can no longer hear from battery energy control module A. Usually a power, ground, or wiring fault — and because this module manages the high-voltage battery, a hybrid or EV may cut power, refuse to charge, or not enter Ready mode.
Read this codeLost Communication with Battery Energy Control Module B
A module on the network can no longer hear from battery energy control module B. Usually a power, ground, or wiring fault — and because this module helps manage the high-voltage battery, a hybrid or EV may cut power, refuse to charge, or not enter Ready mode.
Read this codeLost Communication with Emissions Critical Control Information
A module on the network stopped receiving the emissions-critical data it expects from another controller. Usually a wiring, power, or ground fault on the bus, it can disable emissions monitors, trip the check engine light, and cause a failed inspection.
Read this codeLost Communication with Four-Wheel Drive Clutch Control Module
A module on the network can no longer hear from the four-wheel drive clutch control module. Often a power, ground, or wiring fault — and the AWD/4WD system typically defaults to two-wheel drive with a warning light on.
Read this codeLost Communication with ECM/PCM B
A module on the network can no longer hear from the second engine/powertrain control module (ECM/PCM B). Usually a power, ground, or wiring fault — and because this module helps run the powertrain, the engine may run poorly, lose power, or fail to start.
Read this codeLost Communication with ABS Control Module
A module on the network can no longer hear from the ABS (anti-lock brake) control module. Anti-lock braking, traction control, and stability control are typically disabled — usually a power, ground, or wiring fault at the ABS unit.
Read this codeLost Communication with Vehicle Dynamics Control Module
A module on the network can no longer hear from the vehicle dynamics control module, which runs stability and traction control. Usually a power, ground, or wiring fault, it typically disables ESC/traction control and lights the stability and ABS warnings.
Read this codeLost Communication with Yaw Rate Sensor Module
A module on the network can no longer hear from the yaw rate sensor module, which tells the stability system how fast the vehicle is rotating. Usually a power, ground, or wiring fault, it typically disables stability control and lights the ESC and ABS warnings.
Read this codeLost Communication with Lateral Acceleration Sensor Module
A module on the network can no longer hear from the lateral acceleration sensor module, which measures side-to-side g-force for the stability system. Usually a power, ground, or wiring fault, it typically disables stability control and lights the ESC and ABS warnings.
Read this codeLost Communication with Multi-Axis Acceleration Sensor Module
A module on the network can no longer hear from the multi-axis acceleration sensor — the yaw/lateral-acceleration sensor used by stability control. Often a power, ground, or wiring fault, and stability and traction features typically disable themselves.
Read this codeLost Communication with Steering Angle Sensor Module
A module on the network can no longer hear from the steering angle sensor. Stability control and related systems usually disable themselves and warning lights come on. Usually a power, ground, wiring, or connector fault at the sensor.
Read this codeLost Communication with Park Brake Control Module
A module on the network can no longer hear from the park brake control module, which operates the electronic parking brake. Usually a power, ground, or wiring fault, it can leave the parking brake stuck applied or released and light the brake and EPB warnings.
Read this codeLost Communication with Brake System Control Module
A module on the network can no longer hear from the brake system control module, which runs ABS and works with stability control. Usually a power, ground, or wiring fault, it typically disables ABS and stability control while leaving your base brakes working.
Read this codeLost Communication with Steering Effort Control Module
A module on the network can no longer hear from the steering effort control module, which manages power-steering assist. Usually a power, ground, or wiring fault, it can make the steering heavy or reduce assist and light the power-steering warning.
Read this codeLost Communication with Power Steering Control Module
A module on the network can no longer hear from the power steering control module. Steering assist may be reduced or lost and warning lights come on. Usually a power, ground, wiring, or connector fault at the steering module.
Read this codeLost Communication with Ride Level Control Module
A module on the network can no longer hear from the ride level (suspension height) control module. Usually a power, ground, or wiring fault, it can disable automatic leveling and air suspension and light a suspension warning.
Read this codeLost Communication with Rear Differential Control Module
A module on the network can no longer hear from the rear differential control module (electronic limited-slip / e-diff). Usually a power, ground, or wiring fault, it can disable torque vectoring and traction features and light a warning.
Read this codeLost Communication with Body Control Module (BCM)
A module on the network can no longer hear from the body control module — the computer that runs lighting, locks, windows, and other body electronics. Usually a power, ground, or wiring fault at the BCM.
Read this codeLost Communication with Body Control Module B (BCM B)
A module on the network can no longer hear from a second body control module. Body electrical features tied to that module may stop working and warning lights may appear. Usually a power, ground, wiring, or connector fault at the module.
Read this codeLost Communication with Body Control Module C
A module on the network can no longer hear from body control module C, an additional body controller on feature-rich vehicles. Usually a power, ground, or wiring fault, it can disrupt the body electronics that controller manages.
Read this codeLost Communication with Body Control Module D
A module on the network can no longer hear from body control module D, an additional body controller on feature-rich vehicles. Usually a power, ground, or wiring fault, it can disrupt the body electronics that controller manages.
Read this codeLost Communication with Body Control Module E
A module on the network can no longer hear from body control module E, an additional body controller on feature-rich vehicles. Usually a power, ground, or wiring fault, it can disrupt the body electronics that controller manages.
Read this codeLost Communication with Body Control Module F
A module on the network can no longer hear from body control module F, an additional body controller on feature-rich vehicles. Usually a power, ground, or wiring fault, it can disrupt the body electronics that controller manages.
Read this codeLost Communication with Gateway A
A module on the network can no longer hear from the gateway module that routes messages between the vehicle's communication buses. Because the gateway connects the networks, this can cause widespread communication faults. Usually a power, ground, wiring, or connector fault at the gateway.
Read this codeLost Communication With Gateway B
A module on the network can no longer hear from gateway module 'B', one of the hubs that route messages between the vehicle's communication buses. Because a gateway bridges the networks, this can cause widespread communication faults. Usually a power, ground, wiring, or connector fault at the gateway.
Read this codeLost Communication With Gateway C
A module on the network can no longer hear from gateway module 'C', one of the hubs that route messages between the vehicle's communication buses. Because a gateway bridges the networks, this can cause widespread communication faults. Usually a power, ground, wiring, or connector fault at the gateway.
Read this codeLost Communication With Gateway D
A module on the network can no longer hear from gateway module 'D', one of the hubs that route messages between the vehicle's communication buses. Because a gateway bridges the networks, this can cause widespread communication faults. Usually a power, ground, wiring, or connector fault at the gateway.
Read this codeLost Communication With Gateway E
A module on the network can no longer hear from gateway module 'E', one of the hubs that route messages between the vehicle's communication buses. Because a gateway bridges the networks, this can cause widespread communication faults. Usually a power, ground, wiring, or connector fault at the gateway.
Read this codeLost Communication with Restraints Control Module (Airbags)
A module on the network can no longer hear from the restraints control module — the airbag and seatbelt-pretensioner computer. The airbag warning light comes on and crash protection may be compromised. Diagnose promptly.
Read this codeLost Communication with Restraints Control Module B
A module on the network can no longer hear from restraints control module B, a secondary airbag/restraints controller. Usually a power, ground, or wiring fault, it can disable airbags and pretensioners and light the airbag warning.
Read this codeLost Communication with Restraints Occupant Sensing Control Module
A module on the network can no longer hear from the occupant sensing / classification module that tells the airbag system who is in the seat. Usually a power, ground, or wiring fault, it can disable smart airbag features and light the airbag warning.
Read this codeLost Communication with Instrument Panel Cluster (IPC)
A module on the network can no longer hear from the instrument panel cluster — the gauges and warning-light display. Gauges may go dead or erratic. Usually a power, ground, or wiring fault at the cluster.
Read this codeLost Communication with Information Center / Display Module
A module on the network can no longer hear from the driver information center or display module — the screen that shows trip data, warnings, and settings. Usually a power, ground, fuse, wiring, or connector fault.
Read this codeLost Communication With Parking Assist Control Module
Another module on the network has stopped receiving messages from the parking assist control module — the unit that runs the parking sensors and, on some vehicles, the rear camera and automated parking. Usually a power, ground, wiring, or module fault.
Read this codeLost Communication With Audible Alert / Chime Control Module
Another module on the network has stopped receiving messages from the audible alert (chime) control module — the unit that produces warning chimes and buzzers. Usually a power, ground, wiring, or module fault.
Read this codeLost Communication With Compass Module
Another module on the network has stopped receiving messages from the compass module — the unit that supplies vehicle heading. Usually a power, ground, wiring, or module fault.
Read this codeLost Communication With Navigation Display Module
Another module on the network has stopped receiving messages from the navigation display module — the screen unit that shows maps and route guidance. Usually a power, ground, wiring, or module fault.
Read this codeLost Communication With Navigation Control Module
Another module on the network has stopped receiving messages from the navigation control module — the unit that computes position and routing. Usually a power, ground, wiring, or module fault.
Read this codeLost Communication with HVAC Control Module
A module on the network can no longer hear from the HVAC (heating, ventilation, and air conditioning) control module. Climate control may stop responding. Usually a power, ground, fuse, wiring, or connector fault.
Read this codeLost Communication With HVAC Control Module 'B'
A module on the network can no longer hear from the second HVAC (climate) control module — module 'B'. Often used on multi-zone or rear climate systems. Usually a power, ground, fuse, wiring, or connector fault.
Read this codeLost Communication With Auxiliary Heater Control Module
A module on the network can no longer hear from the auxiliary heater control module — the controller for a supplemental cabin or coolant heater. Cabin warm-up may be slow. Usually a power, ground, fuse, wiring, or connector fault.
Read this codeLost Communication With Vehicle Immobilizer Control Module
Another module has stopped receiving messages from the immobilizer control module — the anti-theft unit that authorizes engine start. Can cause a no-start, since the engine will not run without valid immobilizer authorization.
Read this codeLost Communication with Vehicle Security Control Module
A module on the network can no longer hear from the vehicle security / anti-theft control module. The immobilizer or alarm may misbehave and the engine may not start. Usually a power, ground, wiring, or connector fault.
Read this codeLost Communication With Sunroof Control Module
Another module on the network has stopped receiving messages from the sunroof control module — the unit that operates the power sunroof or moonroof. Usually a power, ground, wiring, or module fault.
Read this codeLost Communication With Restraints System Sensor A
The airbag controller has stopped receiving messages from restraints system sensor A — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor B
The airbag controller has stopped receiving messages from restraints system sensor B — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor C
The airbag controller has stopped receiving messages from restraints system sensor C — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor D
The airbag controller has stopped receiving messages from restraints system sensor D — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor E
The airbag controller has stopped receiving messages from restraints system sensor E — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor F
The airbag controller has stopped receiving messages from restraints system sensor F — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor G
The airbag controller has stopped receiving messages from restraints system sensor G — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor H
The airbag controller has stopped receiving messages from restraints system sensor H — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor I
The airbag controller has stopped receiving messages from restraints system sensor I — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication With Restraints System Sensor J
The airbag controller has stopped receiving messages from restraints system sensor J — a crash/impact sensor that feeds the airbag system. The airbag warning light will be on and deployment behavior may be affected.
Read this codeLost Communication with Radio
A module on the network can no longer hear from the radio/infotainment head unit. Audio, display, and connected features may stop working. Usually a power, ground, fuse, wiring, or connector fault at the radio.
Read this codeLost Communication With Audio Amplifier
A module on the network — usually the radio/head unit — can no longer hear from the external audio amplifier. The sound system typically goes quiet or loses features. It's a comfort/convenience fault, not a driveability or safety problem.
Read this codeLost Communication with Remote Function Actuation (RFA) Module
A module on the network can no longer hear from the Remote Function Actuation (RFA) module — the controller for keyless entry, remote start, and passive entry/push-button start. Remote and key-fob features may stop working.
Read this codeLost Communication With Cruise Control Front Distance Range Sensor
A module on the network can no longer hear from the front distance range sensor — the forward-facing radar that adaptive cruise control and collision-avoidance systems rely on. Those driver-assist features shut off, but normal driving is unaffected.
Read this codeInternal Control Module Software Incompatibility
A control module has detected that the software or calibration versions running across the vehicle's modules don't match what they expect. This is a programming/calibration mismatch — not a wiring fault — and is almost always tied to a recent module replacement, update, or reflash.
Read this codeSoftware Incompatibility With ECM/PCM
A module has detected that the engine/powertrain control module (ECM/PCM) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following an ECM/PCM replacement, update, or reflash.
Read this codeSoftware Incompatibility With Transmission Control Module
A module has detected that the transmission control module (TCM) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a TCM replacement, update, or reflash.
Read this codeSoftware Incompatibility With Transfer Case Control Module
A module has detected that the transfer case control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a transfer case module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Gear Shift Control Module
A module has detected that the gear shift control module (shift-by-wire / gear selector module) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Cruise Control Module
A module has detected that the cruise control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Fuel Injector Control Module
A module has detected that the fuel injector control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Glow Plug Control Module
A module has detected that the glow plug control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a glow plug module replacement, update, or reflash on a diesel.
Read this codeSoftware Incompatibility With Throttle Actuator Control Module
A module has detected that the throttle actuator control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a throttle module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Alternative Fuel Control Module
A module has detected that the alternative fuel control module (CNG, LPG, or other gaseous-fuel system controller) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Fuel Pump Control Module
A module has detected that the fuel pump control module (FPCM / fuel pump driver module) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Drive Motor Control Module
A module has detected that the drive motor control module (the inverter/motor controller in a hybrid or electric vehicle) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Battery Energy Control Module A
A module has detected that battery energy control module 'A' — the high-voltage battery management controller on a hybrid or EV — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Battery Energy Control Module B
A module has detected that battery energy control module 'B' — a second high-voltage battery management controller on a hybrid or EV — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Four-Wheel Drive Clutch Control Module
A module has detected that the four-wheel drive clutch control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a 4WD/AWD module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Anti-Lock Brake System (ABS) Control Module
A module has detected that the anti-lock brake system (ABS) control module is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following an ABS module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Vehicle Dynamics Control Module
A module has detected that the vehicle dynamics control module — the electronic stability control (ESC/ESP) controller — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Park Brake Control Module
A module has detected that the park brake control module — the electronic parking brake (EPB) controller — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch — not a wiring fault — usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Brake System Control Module
A module has detected that the brake system control module — the ABS/electronic brake controller — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, and usually shows up after a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Steering Effort Control Module
A module has detected that the steering effort control module — the controller that manages how much steering assist and effort the driver feels — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Power Steering Control Module
A module has detected that the power steering control module — the electric power steering (EPS) controller — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Ride Level Control Module
A module has detected that the ride level control module — the controller for air or adaptive suspension and vehicle ride height — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Body Control Module
A module has detected that the body control module (BCM) — the controller for lighting, locks, wipers, and many body electrical features — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Instrument Panel Control Module
A module has detected that the instrument panel control module — the gauge cluster / IPC — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a cluster replacement, update, or reflash.
Read this codeSoftware Incompatibility With HVAC Control Module
A module has detected that the HVAC control module — the climate-control (heating, ventilation, and air conditioning) controller — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Auxiliary Heater Control Module
A module has detected that the auxiliary heater control module — the controller for a supplemental cabin/engine heater such as an electric PTC or fuel-fired booster heater — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Vehicle Immobilizer Control Module
A module has detected that the vehicle immobilizer control module — the anti-theft controller that authenticates the key/fob before allowing the engine to start — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Vehicle Security Control Module
A module has detected that the vehicle security control module — the controller behind the alarm system, keyless entry, and anti-theft door locking — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Steering Angle Sensor Module
A module has detected that the steering angle sensor module — which reports how far and how fast the steering wheel is turned to stability control, power steering, and ADAS systems — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Steering Column Control Module
A module has detected that the steering column control module — which manages functions like electric tilt/telescope, steering lock, and column-mounted controls — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Tire Pressure Monitor Module
A module has detected that the tire pressure monitor (TPMS) module — which reads each tire's pressure sensor and controls the low-tire-pressure warning light — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring or sensor fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Body Control Module 'A'
A module has detected that body control module A — one of the vehicle's primary body electrical controllers, or the first of two BCMs on vehicles with a split/dual-BCM architecture — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Multi-axis Acceleration Sensor Module 'A'
A module has detected that multi-axis acceleration sensor module A — which measures lateral, longitudinal, and/or vertical acceleration for stability control and ride/handling systems — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Gear Shift Control Module 'B'
A module has detected that gear shift control module B — the second of two shift-related controllers on vehicles with split or redundant shift-by-wire/gear-selector electronics — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Radio
A module has detected that the radio/infotainment head unit is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a head unit replacement, update, or reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Pack Sensor Module
On a hybrid or electric vehicle, a module has detected that the high-voltage battery pack sensor module — which monitors individual cell voltages, temperatures, and pack current — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a battery service, module replacement, or reflash.
Read this codeSoftware Incompatibility With Restraints Control Module
A module has detected that the restraints control module (airbag control module) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, but because this module governs airbag and seatbelt pretensioner deployment, it's treated as a high-priority, safety-relevant code.
Read this codeSoftware Incompatibility With Battery Charger Control Module A
On a plug-in hybrid or electric vehicle, a module has detected that battery charger control module A — the onboard charger that converts AC power from a wall outlet or charging station into DC power for the high-voltage battery — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a charger module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Remote Function Actuation Module
A module has detected that the remote function actuation (RFA) module — which handles keyless entry, key fob commands, and often remote start and passive entry — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Body Control Module 'B'
A module has detected that body control module B — the second of two body electronics controllers on vehicles with split BCM architecture — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a module replacement, update, or reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module A
On a hybrid or electric vehicle, a module has detected that battery interface control module A — which handles high-voltage contactor control and the connection between the battery pack and the rest of the powertrain — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a battery service, module replacement, or reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module B
On a hybrid or electric vehicle, a module has detected that battery interface control module B — the second of two contactor/interface controllers on vehicles with a more complex or dual-pack high-voltage architecture — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following a battery service, module replacement, or reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module C
On a hybrid or electric vehicle with a multi-segment high-voltage battery architecture, a module has detected that battery interface control module C is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module D
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module D is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module E
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module E is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module F
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module F is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module G
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module G is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module H
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module H is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module I
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module I is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module J
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module J is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module K
On a hybrid or electric vehicle with a heavily segmented high-voltage battery pack, a module has flagged battery interface control module K as running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, and usually follows battery service, a module swap, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module L
On a hybrid or electric vehicle with a heavily segmented high-voltage battery pack, battery interface control module L has been found to be running a software or calibration version that doesn't match the rest of the vehicle's modules. This is a programming mismatch rather than a wiring or communication failure, typically appearing after battery service, a module swap, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module M
On a hybrid or electric vehicle with a heavily segmented high-voltage battery pack, battery interface control module M is running a software or calibration version that doesn't match the rest of the vehicle's modules. This points to a programming mismatch rather than a wiring problem, and typically follows battery service, a module swap, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module N
On a hybrid or electric vehicle with a heavily segmented high-voltage battery pack, battery interface control module N has been found running a software or calibration version outside the set the rest of the vehicle's modules expect. This is a programming mismatch, not a wiring fault, typically appearing after battery service, a module swap, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module O
On a hybrid or electric vehicle with a heavily segmented high-voltage battery pack, battery interface control module O has been found running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch rather than a wiring fault, and it typically shows up after battery service, a module swap, or a reflash.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Interface Control Module P
On a hybrid or electric vehicle with an unusually heavily segmented high-voltage battery pack, battery interface control module P — the final module in this lettered series — has been found running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch rather than a wiring fault, typically following battery service, a module swap, or a reflash.
Read this codeSoftware Incompatibility With Engine Disconnect Clutch
On a hybrid vehicle whose gasoline engine can be mechanically coupled to and decoupled from the drivetrain, the module that controls the engine disconnect clutch is running software or a calibration that doesn't match the rest of the vehicle's modules. This is a programming mismatch rather than a wiring fault, and it typically follows transmission or hybrid drivetrain service.
Read this codeSoftware Incompatibility With Brake Booster Control
The module that controls the vehicle's electric brake booster is running software or a calibration that doesn't match the rest of the vehicle's modules. This is a programming mismatch rather than a mechanical brake fault, but because it involves brake pedal assist, it should be treated as a higher-priority repair even though the vehicle typically remains driveable.
Read this codeSoftware Incompatibility With Battery Energy Control Module C
A module has detected that battery energy control module 'C' — one of the controllers that manages the high-voltage battery on a hybrid or EV — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, and usually follows a module replacement, pack service, update, or reflash.
Read this codeSoftware Incompatibility With Vehicle Thermal Management Control Module
The module that coordinates cooling and heating across the engine, transmission, battery, and cabin systems is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch rather than a mechanical cooling-system fault, and it usually follows a module replacement or software update.
Read this codeSoftware Incompatibility With Active Grille Air Shutter Module A
The module that opens and closes the vehicle's active grille shutters — the movable vanes behind the front grille that improve aerodynamics and warm-up time — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, and the vehicle remains fully driveable.
Read this codeSoftware Incompatibility With Active Grille Air Shutter Module B
The module that opens and closes a second set of active grille shutters — motorized vanes behind the grille that improve aerodynamics and warm-up time — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, and the vehicle remains fully driveable.
Read this codeSoftware Incompatibility With Active Grille Air Shutter Module C
The module that opens and closes a third set of active grille shutters — motorized vanes behind the grille that improve aerodynamics and warm-up time — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, and the vehicle remains fully driveable.
Read this codeSoftware Incompatibility With Active Grille Air Shutter Module D
The module that opens and closes a fourth set of active grille shutters — motorized vanes behind the grille that improve aerodynamics and warm-up time — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, and the vehicle remains fully driveable.
Read this codeSoftware Incompatibility With NOx Sensor C
A third nitrogen oxide (NOx) sensor module used for diesel or lean-burn emissions control is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a failed sensor, but because it affects emissions monitoring it should be treated as more than a cosmetic issue.
Read this codeSoftware Incompatibility With Ion Sense Module
The module that uses ion-sensing technology to monitor combustion — detecting misfire, knock, or air-fuel conditions through the spark plug circuit itself rather than a separate sensor — is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, and the vehicle usually remains driveable.
Read this codeSoftware Incompatibility With Hybrid/EV Battery Inductive Charger Control Module
The module that manages wireless (inductive) charging of the hybrid or EV high-voltage battery is communicating on the network, but its software or calibration doesn't match what the rest of the vehicle's modules expect. It's a programming mismatch, not a wiring fault, and the vehicle usually remains driveable.
Read this codeInvalid Data Received from ECM/PCM A
A module is receiving messages from the engine/powertrain control module, but the data is implausible or out of range. The connection is alive — the content is wrong. Often a sensor, calibration, or internal fault driving bad data, or a network issue corrupting it.
Read this codeInvalid Data Received from Transmission Control Module
A module is receiving messages from the transmission control module (TCM), but the data is implausible or out of range. The connection is alive — the content is wrong. Often a sensor, calibration, or internal fault driving bad data, or a network issue corrupting it.
Read this codeInvalid Data Received From Transfer Case Control Module
A module is receiving messages from the transfer case control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Common on 4WD/AWD trucks and SUVs after sensor faults, low voltage, or module programming issues.
Read this codeInvalid Data Received From Gear Shift Control Module A
A module is receiving messages from the gear shift control module — the electronic shifter on shift-by-wire vehicles — but the data is implausible or out of range. Because gear selection is safety-relevant, many vehicles react conservatively, sometimes refusing to shift out of Park.
Read this codeInvalid Data Received From Cruise Control Module
A module is receiving messages from the cruise control module, but the data is implausible or out of range. Cruise control typically disables itself as a precaution. The car drives normally otherwise — this is a convenience-system fault, not a driveability emergency.
Read this codeInvalid Data Received From Fuel Injector Control Module
A module is receiving messages from the fuel injector control module (FICM), but the data is implausible or out of range. Most common on diesels with a dedicated injector driver module. Can cause hard starts, rough running, or reduced power depending on which data is invalid.
Read this codeInvalid Data Received From Glow Plug Control Module 1
A module is receiving messages from the glow plug control module on a diesel engine, but the data is implausible or out of range. The usual result is hard cold starting and a glow plug warning light. A diesel-only code — the connection is alive, the content is wrong.
Read this codeInvalid Data Received From Throttle Actuator A Control Module
A module is receiving messages from the throttle actuator control module, but the data is implausible or out of range. Because throttle control is safety-relevant, the vehicle typically responds with reduced power or limp mode until the data can be trusted again.
Read this codeInvalid Data Received From Alternative Fuel Control Module
A module is receiving messages from the alternative fuel control module, but the data inside them is implausible or out of range. Seen on CNG, LPG/propane, and bi-fuel vehicles. The connection is alive — the content is wrong.
Read this codeInvalid Data Received From Air Conditioning (A/C) Control Module
A module is receiving messages from the air conditioning (A/C) control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Usually a comfort-only fault.
Read this codeInvalid Data Received From Exhaust Gas Recirculation Control Module 'A'
A module is receiving messages from exhaust gas recirculation (EGR) control module 'A', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Emissions-relevant.
Read this codeInvalid Data Received From Exhaust Gas Recirculation Control Module 'B'
A module is receiving messages from exhaust gas recirculation (EGR) control module 'B', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Emissions-relevant.
Read this codeInvalid Data Received From Turbocharger/Supercharger Control Module 'A'
A module is receiving messages from turbocharger/supercharger control module 'A', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Can affect boost and power.
Read this codeInvalid Data Received From Turbocharger/Supercharger Control Module 'B'
A module is receiving messages from turbocharger/supercharger control module 'B', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Can affect boost and power.
Read this codeInvalid Data Received From Reductant Control Module
A module is receiving messages from the reductant (diesel exhaust fluid) control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Seen on diesels with SCR emissions systems.
Read this codeInvalid Data Received From Fuel Pump Control Module
A module is receiving messages from the fuel pump control module, but the data inside them is implausible or out of range. Common on vehicles with an electronic returnless or demand-based fuel system. The connection is alive — the content is wrong.
Read this codeInvalid Data Received From Drive Motor Control Module
A module is receiving messages from the drive motor control module, but the data inside them is implausible or out of range. Found on hybrids and EVs, where this module runs the traction motor. The connection is alive — the content is wrong. High-voltage system: professional diagnosis.
Read this codeInvalid Data Received From Battery Energy Control Module A
A module is receiving messages from battery energy control module A, but the data inside them is implausible or out of range. Found on hybrids and EVs, where this module manages the high-voltage pack. The connection is alive — the content is wrong. High-voltage system: professional diagnosis.
Read this codeInvalid Data Received From Battery Energy Control Module B
A module is receiving messages from battery energy control module B, but the data inside them is implausible or out of range. Seen on hybrids and EVs that use more than one battery supervisor. The connection is alive — the content is wrong. High-voltage system: professional diagnosis.
Read this codeInvalid Data Received From Four-Wheel Drive Clutch Control Module
A module is receiving messages from the four-wheel-drive clutch control module, but the data inside them is implausible or out of range. Common on AWD/4WD vehicles with an electronically controlled coupling. The connection is alive — the content is wrong.
Read this codeInvalid Data Received from Anti-Lock Brake System (ABS) Control Module
A module is receiving messages from the ABS control module, but the data — wheel speeds or brake status — is implausible or out of range. The link is alive; the content is wrong. Often a wheel speed sensor, calibration, or internal ABS fault.
Read this codeInvalid Data Received from Vehicle Dynamics Control Module
A module is receiving messages from the vehicle dynamics (stability control) module, but the data — yaw, lateral acceleration, or stability status — is implausible or out of range. The link is alive; the content is wrong. Often a sensor, calibration, or internal fault.
Read this codeInvalid Data Received From Park Brake Control Module
A module is receiving messages from the electronic park brake control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Because it touches the parking brake and can affect ABS/stability data, treat it seriously.
Read this codeInvalid Data Received from Brake System Control Module
A module is receiving messages from the brake system control module (ABS/ESC), but the data is implausible or out of range. The connection is alive — the content is wrong. Often a wheel-speed sensor, calibration, or internal fault driving bad data, or a network issue corrupting it.
Read this codeInvalid Data Received From Steering Effort Control Module
A module is receiving messages from the steering effort control module, but the data inside them is implausible or out of range. This module tunes power-steering assist. The connection is alive — the content is wrong.
Read this codeInvalid Data Received From Exhaust Gas Sensor Module
A module is receiving messages from the exhaust gas sensor module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong.
Read this codeInvalid Data Received From Rocker Arm Control Module 'A'
A module is receiving messages from rocker arm control module 'A', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Related to variable valve lift and cylinder deactivation systems.
Read this codeInvalid Data Received From Rocker Arm Control Module 'B'
A module is receiving messages from rocker arm control module 'B', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. This is the 'B' counterpart to U041C.
Read this codeInvalid Data Received From All Wheel Drive Control Module
A module is receiving messages from the all-wheel drive control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong.
Read this codeInvalid Data Received From Power Steering Control Module A
A module is receiving messages from the power steering control module, but the data is implausible or out of range. Electric power steering may reduce or suspend assist as a precaution — the wheel gets heavy but the car still steers. The connection is alive; the content is wrong.
Read this codeInvalid Data Received From Suspension Control Module 'A'
A module is receiving messages from suspension control module 'A', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Seen on vehicles with adaptive dampers or air suspension.
Read this codeInvalid Data Received from Body Control Module
A module is receiving messages from the body control module (BCM), but the data is implausible or out of range. The connection is alive — the content is wrong. Often a switch, sensor, calibration, or internal fault driving bad data, or a network issue corrupting it.
Read this codeInvalid Data Received from Instrument Panel Control Module
A module is still hearing from the instrument panel cluster (IPC), but the data inside those messages is implausible or out of range. The link is alive — the content is wrong. Usually a sensor input, calibration, or internal cluster fault, or a network issue corrupting the data.
Read this codeInvalid Data Received from HVAC Control Module
A module is still hearing from the HVAC (heating, ventilation, and air conditioning) control module, but the data is implausible or out of range. The link is alive — the content is wrong. Usually a climate sensor, calibration, or internal fault, or a network issue corrupting the data.
Read this codeInvalid Data Received From Auxiliary Heater Control Module
A module is receiving messages from the auxiliary heater control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. A comfort-system fault, rarely a driveability problem.
Read this codeInvalid Data Received from Immobilizer / Vehicle Security Control Module
A module is receiving messages from the immobilizer / vehicle security control module, but the data is implausible, out of range, or fails authentication. The connection is alive — the content is wrong. Often a key, calibration, or programming fault, or a network issue corrupting it.
Read this codeInvalid Data Received From Vehicle Security Control Module
A module is receiving messages from the vehicle security control module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Can affect the anti-theft system and, occasionally, starting.
Read this codeInvalid Data Received from Steering Angle Sensor Module
A module is still hearing from the steering angle sensor, but the steering-position data is implausible or out of range. The link is alive — the content is wrong. Often an uncalibrated or failing sensor, or a network issue corrupting the data. Stability and steering-assist features may disable themselves.
Read this codeInvalid Data Received from Steering Column Control Module
A module is still hearing from the steering column control module, but the data is implausible or out of range. The link is alive — the content is wrong. Often a column sensor, calibration, or internal fault, or a network issue corrupting the data. Steering and stability features may disable themselves.
Read this codeInvalid Data Received From V2X Module
A module is receiving messages from the V2X (vehicle-to-everything) communication module, but the data inside them is implausible or out of range. The connection is alive — the content is wrong. A connectivity/telematics fault.
Read this codeInvalid Data Received From Chassis Control Module 'A'
A module is receiving messages from chassis control module 'A', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Can affect ride, handling, and stability features.
Read this codeInvalid Data Received From Chassis Control Module 'B'
A module is receiving messages from chassis control module 'B', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Can affect ride, handling, and stability features.
Read this codeInvalid Data Received From Active Vibration Control Module
A module is receiving messages from the active vibration control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Mostly affects ride smoothness and cabin noise, not driveability.
Read this codeInvalid Data Received From Generator Control Module 'A'
A module is receiving messages from generator (charging) control module 'A', but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect charging and electrical stability.
Read this codeInvalid Data Received From Camshaft Position Control Module
A module is receiving messages from the camshaft position control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect variable valve timing and driveability.
Read this codeInvalid Data Received From Tire Pressure Monitor Module
A module is receiving messages from the tire pressure monitor (TPMS) module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. A monitoring-only fault that does not affect driveability.
Read this codeInvalid Data Received From Body Control Module 'A'
A module is receiving messages from body control module 'A', but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect a wide range of body electrical features.
Read this codeInvalid Data Received From Multi-axis Acceleration Sensor Module 'A'
A module is receiving messages from the multi-axis acceleration sensor module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can disable stability control and related safety systems.
Read this codeInvalid Data Received From Cruise Control Front Distance Range Sensor
A module is receiving messages from the cruise control front distance range sensor, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can disable adaptive cruise and forward-collision features.
Read this codeInvalid Data Received From Active Roll Control Module
A module is receiving messages from the active roll control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect body-roll control and handling in corners.
Read this codeInvalid Data Received From Power Steering Control Module (Rear)
A module is receiving messages from the rear power steering control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can reduce or disable rear steering assist.
Read this codeInvalid Data Received From Differential Control Module (Front)
A module is receiving messages from the front differential control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect front-axle torque delivery and traction.
Read this codeInvalid Data Received From Differential Control Module (Rear)
A module is receiving messages from the rear differential control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect rear-axle torque delivery and traction.
Read this codeInvalid Data Received From Trailer Brake Control Module
A module is receiving messages from the trailer brake control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect integrated trailer braking while towing.
Read this codeInvalid Data Received From All Terrain Control Module
A module is receiving messages from the all terrain control module, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect terrain drive modes and off-road assist features.
Read this codeInvalid Data Received From Suspension Control Module 'B'
A module is receiving messages from suspension control module 'B', but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can affect ride height, damping, and handling.
Read this codeInvalid Data Received From Cruise Control Front Distance Range Sensor (Left)
A module is receiving messages from the left front distance range sensor, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can disable adaptive cruise and forward safety features.
Read this codeInvalid Data Received From Cruise Control Front Distance Range Sensor (Right)
A module is receiving messages from the right front distance range sensor, but the data inside them is implausible or out of range. The link is alive — the content is wrong. Can disable adaptive cruise and forward safety features.
Read this codeInvalid Data Received From Accelerator Pedal Module
A module — usually the engine computer — is receiving messages from the accelerator pedal module, but the throttle-demand data inside them is implausible or out of range. The link is alive; the content is wrong. The vehicle may drop into a reduced-power fail-safe.
Read this codeInvalid Data Received From Vacuum Sensor A
A module is receiving messages from vacuum sensor 'A', but the pressure/vacuum data inside them is implausible or out of range. The link is alive; the content is wrong. Can affect brake-boost, EVAP, or boost-related monitoring depending on the vehicle.
Read this codeInvalid Data Received From Vacuum Sensor B
A module is receiving messages from vacuum sensor 'B', but the pressure/vacuum data inside them is implausible or out of range. The 'B' counterpart to U043E — same fault pattern, a second sensor location or system.
Read this codeInvalid Data Received From Pedestrian Alert Control Module
A module is receiving messages from the pedestrian alert control module, but the data inside them is implausible or out of range. The link is alive; the content is wrong. Affects the low-speed warning sound on hybrids and EVs, not core driving.
Read this codeInvalid Data Received From Emissions Critical Control Information
A module is receiving emissions-critical control information over the network, but the data inside those messages is implausible or out of range. The link is alive; the content is wrong. Can affect emissions monitoring and readiness.
Read this codeInvalid Data Received From ECM/PCM 'B'
A module is receiving messages from the secondary engine/powertrain computer (ECM/PCM 'B'), but the data inside them is implausible or out of range. The link is alive; the content is wrong. The 'B' counterpart to U0401.
Read this codeInvalid Data Received From Body Control Module 'B'
A module is receiving messages from body control module 'B', but the data inside them is implausible or out of range. The link is alive; the content is wrong. The 'B' counterpart to U0431 — a second body controller on vehicles that use more than one.
Read this codeInvalid Data Received From Body Control Module 'C'
A module is receiving messages from body control module 'C', but the data inside them is implausible or out of range. The link is alive; the content is wrong. The 'C' counterpart to U0431/U0443 — a third body controller on feature-rich vehicles.
Read this codeInvalid Data Received From Body Control Module 'D'
A module is receiving messages from body control module 'D', but the data inside them is implausible or out of range. The link is alive; the content is wrong. The 'D' counterpart to U0431/U0443/U0444 — a fourth body controller on very feature-rich vehicles.
Read this codeInvalid Data Received From Body Control Module 'E'
A module is receiving messages from body control module 'E', but the data inside them is implausible or out of range. The link is alive; the content is wrong. The 'E' counterpart to U0431/U0443/U0444/U0445 — a fifth body controller on the most complex vehicles.
Read this codeInvalid Data Received From Gateway 'A'
A module is receiving messages relayed by gateway 'A', but the data inside them is implausible or out of range. The link is alive; the forwarded content is wrong. Because a gateway bridges several networks, this code is very often secondary to a fault on one of the buses it connects.
Read this codeInvalid Data Received From Gateway 'B'
A module is receiving messages relayed by gateway 'B', but the data inside them is implausible or out of range. The link is alive; the forwarded content is wrong. The 'B' counterpart to U0447 — a second gateway on vehicles that split routing across more than one.
Read this codeInvalid Data Received From Gateway 'C'
A module is receiving messages relayed by gateway 'C', but the data inside them is implausible or out of range. The link is alive; the forwarded content is wrong. The 'C' counterpart to U0447/U0448 — a third gateway on vehicles that split routing across several.
Read this codeInvalid Data Received From Gateway 'D'
A module is receiving messages relayed by gateway 'D', but the data inside them is implausible or out of range. The link is alive; the forwarded content is wrong. The 'D' counterpart to U0447/U0448/U0449 — a fourth gateway on the most network-heavy vehicles.
Read this codeInvalid Data Received From Gateway 'E'
A module is receiving messages relayed by gateway 'E', but the data inside them is implausible or out of range. The link is alive; the forwarded content is wrong. The 'E' counterpart to U0447-U044A — the fifth gateway, and the one whose number jumps past the reserved gap to U0451.
Read this codeInvalid Data Received From Restraints Control Module
A module is receiving messages from the restraints (airbag/SRS) control module, but the data inside them is implausible or out of range. The link is alive; the content is wrong. Because this module governs airbags and seatbelt pretensioners, treat it as safety-critical and diagnose it promptly.
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About this code library
AutoLogicTools code pages provide general OBD-II trouble code information for planning conversations with a mechanic. A scan-tool reading is only the starting point. Verify diagnoses, parts, and labor with a qualified automotive professional before approving any repair.