OBD-II trouble code
P0339: Crankshaft Position Sensor "A" Circuit Intermittent
The crankshaft position signal cuts out momentarily and then returns. Because the crank sensor is the engine's master timing reference, even a brief dropout can cause a sudden stall, a no-start, or a hard-to-reproduce hesitation — treat it as a stranding risk.
Quick facts
- System
- Powertrain
- Category
- Sensors / Timing
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $150 – $500
- DIY difficulty
- Intermediate DIY
What does P0339 mean?
The crankshaft position (CKP) sensor reads a toothed reluctor wheel on the crankshaft and tells the powertrain control module (PCM) exactly where the pistons are and how fast the engine is turning. Every ignition event and every injector pulse is scheduled off that signal, and misfire detection depends on it as well. There is no graceful fallback: when the crank signal disappears, the PCM has nothing to time against, and the engine simply stops.
P0339 is the intermittent member of the CKP-A family. P0335 is a general circuit fault — no usable signal at all. P0336 is a range/performance complaint, where the pulse pattern exists but is implausible. P0337 and P0338 cover a signal stuck too low or too high. P0339 says the signal was present and correct, dropped out or went erratic for a moment, and then came back. The PCM captured the event and logged it.
That intermittent character is what makes this code both frustrating and genuinely serious. Frustrating because the circuit almost always measures perfectly in the shop; serious because the failure mode when it happens at speed is an engine that quits without warning. Drivers typically describe an engine that dies at a stoplight or on the highway, then restarts fine a few minutes later, or a no-start that resolves itself after the car sits.
Heat is the recurring theme. A crank sensor with a degrading internal winding or a hairline-cracked body frequently works cold and drops out once it heat-soaks — the classic pattern of stalling after 20 or 30 minutes of driving and restarting once things cool. Connector and wiring problems produce the same symptom: corroded terminals, a partially seated connector, or insulation chafed against a bracket that only makes or breaks contact under vibration or thermal expansion. Mechanical causes are just as common as electrical ones. A reluctor wheel with a chipped, worn, or debris-packed tooth glitches at the same point in every revolution, and an air gap that has opened up — from a loose sensor mount, a shifted bracket, or metal debris on the sensor tip — weakens the signal until it drops out under vibration.
Because the consequence of the next dropout is a stall, this code should be treated as do-not-rely-on-the-vehicle. It is not a code to drive on for weeks while you think about it.
Common causes
- Crankshaft position sensor degrading internally — works cold, drops out once heat-soaked (the most common single cause)
- Corroded, partially seated, or damaged sensor connector
- Chafed or broken sensor wiring, particularly where the harness passes near the exhaust or a bracket
- Damaged, worn, or debris-packed teeth on the reluctor / tone wheel
- Excessive or inconsistent air gap between the sensor and the reluctor wheel
- Metal debris clinging to the magnetic sensor tip, distorting the waveform
- Loose sensor mounting bolt or a shifted mounting bracket
- Electrical noise from ignition components, a failing alternator, or aftermarket wiring bleeding onto the signal circuit
- Timing chain or belt wear letting the crank-to-cam relationship drift enough to corrupt sync
Symptoms
- Check engine light on, sometimes intermittently
- Sudden stall with no warning, often followed by a normal restart minutes later
- Intermittent no-start — the engine cranks but won't fire, then starts fine after it sits
- Extended cranking before the engine catches
- Random hesitation, stumble, or brief loss of power while driving
- Tachometer needle dropping to zero or flickering while the engine is still running
- Symptoms that appear only when the engine is fully warmed up
- Companion misfire codes logged at the same timestamp as the dropout
Diagnostic steps
- 1.Scan and record all codes and freeze-frame data. Engine temperature and RPM at the moment of the fault tell you whether this is a heat-related dropout or a vibration-related one.
- 2.Graph the engine speed PID on a scan tool during a road test that reproduces the conditions from the freeze frame. A momentary drop to zero RPM with the engine still turning confirms a signal dropout.
- 3.Better still, put a scope on the CKP signal wire and capture the waveform while driving or while the engine heat-soaks. A glitch that repeats at the same point in every revolution points at the reluctor wheel rather than the sensor.
- 4.Inspect the sensor connector for corrosion, moisture, spread pins, and full seating. Wiggle-test the connector and harness with the waveform on screen.
- 5.Follow the harness from the sensor to the PCM looking for chafe points, especially near exhaust components and mounting brackets where heat and vibration are worst.
- 6.Remove the sensor and inspect the tip for metal debris and for cracks or heat damage to the body. Clean any debris off a magnetic tip.
- 7.Check the air gap and confirm the sensor mounting bolt is present and torqued to specification, and that the bracket has not shifted.
- 8.Inspect the reluctor wheel where it is visible for chipped, worn, or missing teeth and for packed debris between teeth.
- 9.If the vehicle stalls when hot, try a targeted heat test: warm the engine, then use a heat gun on the sensor while watching the signal, or spray the sensor with a cooling agent when it acts up. A signal that recovers when cooled confirms a heat-sensitive sensor.
- 10.Replace the crank sensor only after the connector, harness, air gap, and reluctor wheel have been checked — a new sensor in a bad connector fails the same way.
Repair cost
$150 – $500
The sensor itself is usually $30 to $180. Where it mounts determines the labor: sensors reachable from above or with easy underside access put a full replacement at roughly $150 to $350, while sensors tucked behind the starter, under the intake, or behind accessory drives push it to $350 to $500. A connector or wiring repair, when that is the real fault, runs $100 to $400. Reluctor wheel damage is the expensive branch — on many vehicles the wheel is on the flexplate or crankshaft and requires transmission removal, which runs well into the thousands.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with crankshaft 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.