OBD-II trouble code
P0223: Throttle/Pedal Position Sensor/Switch 'B' Circuit High
The second throttle or accelerator pedal position sensor is reporting a voltage above its maximum allowed value — usually pinned near the 5-volt reference. The check engine light is on and the vehicle almost always drops into reduced-power limp mode.
Quick facts
- System
- Powertrain
- Category
- Throttle / Idle
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $650
- DIY difficulty
- Intermediate DIY
What does P0223 mean?
Drive-by-wire vehicles have no cable between the pedal and the throttle plate. Instead, redundant position sensors at the accelerator pedal and inside the throttle body each report a voltage that rises and falls with angle, and the control module cross-checks them against each other before acting on anything. The 'B' circuit is one of those redundant signals. In normal operation its voltage lives inside a defined window — commonly somewhere around 0.5 volts at rest and 4.5 volts at full travel, with the exact numbers varying by platform.
P0223 sets when the module sees the 'B' signal exceed the maximum threshold, typically in the 4.65 to 4.8 volt neighborhood, for a short qualifying period measured in fractions of a second. That is the electrical signature of a signal wire that has found the 5-volt reference: a short between signal and reference inside a chafed harness, a connector flooded with water bridging two pins, a lost sensor ground that lets the signal float up, or a sensor whose internal element has failed open at the high end of its sweep.
It helps to place this code among its neighbors, because the four codes in the 'B' block are not interchangeable. P0220 is the general circuit code. P0221 is range/performance — the signal is present and plausible on its own, but it does not agree with what the other sensors are reporting. P0222 is the low-voltage fault. P0223 is its mirror image: the voltage is too high. And P0224 says the fault comes and goes rather than staying put. Knowing which one you have narrows the wiring you need to look at before you pick up a meter.
One diagnostic asymmetry is worth stating plainly. A low-voltage code can be produced by an open circuit, a short to ground, or a dead sensor — three quite different faults. A high-voltage code has a much shorter list, because something has to actively push the signal up. In practice that means a short to the reference or to another voltage source, or a ground path that has gone high-resistance or opened entirely. That is why checking the sensor ground with a loaded voltage-drop test is worth doing early on this code specifically.
Because the module cannot trust a throttle-demand signal that reads implausibly high, it will not act on it. Expect a reduced-power state, a capped RPM ceiling, disabled cruise control, and a fail-safe code from the P2104 through P2110 group stored alongside this one. The vehicle remains driveable but noticeably down on power until the circuit fault is repaired.
Common causes
- Short between the 'B' signal wire and the 5-volt reference or another voltage source
- Open or high-resistance sensor ground allowing the signal to float high
- Water intrusion or corrosion in the pedal or throttle-body connector bridging adjacent pins
- Chafed harness where the signal wire has rubbed through against an adjacent circuit
- Failed accelerator pedal position (APP) sensor with an internally open element
- Failed throttle position sensor inside the throttle body
- Spread, backed-out, or pushed-back terminal in the sensor connector
- Wiring damage from recent under-dash or intake work near the pedal or throttle body
- Rodent damage to the engine-bay harness
- Rarely, a control module with a failed internal analog-to-digital input
Symptoms
- Check engine light is on, often illuminating the moment the fault occurs while driving
- Reduced engine power warning on the dash
- Limp mode with throttle response capped regardless of pedal input
- Poor or completely unresponsive acceleration
- Rough or unstable idle
- Cruise control disabled
- Engine may stall on deceleration or refuse to rev past a low RPM ceiling
- Companion codes such as P0220, P0221, or a P2104-P2110 fail-safe code
Diagnostic steps
- 1.Scan every module and record all stored and pending codes with freeze frame data. P0223 alongside P0221 or P0222 points at one circuit; 'A' codes stored with it point at something the sensors share.
- 2.Confirm in service data which physical sensor your manufacturer designates 'B'. On many platforms it is the second element inside the accelerator pedal assembly, on others it is in the throttle body — verify before ordering a part.
- 3.Inspect both the pedal and throttle-body connectors for moisture, green corrosion, bent or backed-out pins, and a properly seated locking tab. Water bridging pins is a classic cause of a high-voltage code.
- 4.With the key on and engine off, back-probe the 'B' signal wire. A reading sitting at or very near the 5-volt reference confirms the code and points at a short to reference or a lost ground.
- 5.Perform a voltage-drop test on the sensor ground with the circuit loaded. On a high-voltage code specifically, a resistive or open ground is a leading suspect and an ohmmeter alone will not always reveal it.
- 6.Unplug the sensor and check the signal wire for voltage with the key on. If the signal wire is still high with nothing connected, the short is in the harness, not the sensor.
- 7.Check continuity and isolation between the signal wire and the 5-volt reference wire with the connectors separated at both ends.
- 8.Wiggle-test the harness along its full run — especially where it passes a bracket, a bulkhead grommet, or a hinge point — with live data displayed.
- 9.Compare the 'A' and 'B' signals graphed together while sweeping the pedal slowly through full travel. Two traces that should mirror or track each other will show exactly where the 'B' channel departs.
- 10.If wiring, reference, and ground all test good and the signal is still high, replace the affected pedal assembly or throttle body and perform the required relearn procedure.
Repair cost
$100 – $650
Diagnosis typically runs $75-$150. Connector and wiring repairs are often the cheapest outcome, in the $100-$300 range with diagnostic time, and they are more likely on a high-voltage code than most people expect. An accelerator pedal position sensor or pedal assembly is roughly $150-$400 installed on mainstream vehicles. A throttle body is generally $250-$650 installed and can be more on luxury platforms. Many vehicles require a throttle or pedal relearn afterward, so budget for it.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with accelerator pedal position sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.