P0336
PowertrainCrankshaft Position Sensor A Circuit Range/Performance
The crankshaft position sensor tells the ECU exactly where the crank is in its rotation, which the ECU uses to time the spark and the injectors. With P0336 the sensor is still talking, but the signal is erratic or doesn't match what the ECU expects, often showing a missing or extra pulse where the reluctor ring has a tooth. When the timing reference goes wonky like this you get hard starts, stalling, and an engine that can drop into limp mode without warning.
ⓘ Information only. This page provides general educational information about fault code P0336. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0336 mean?
P0336 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Crankshaft Position Sensor A Circuit Range/Performance.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light, sometimes flashing if the misfire is bad enough
- • Long cranking before it fires, or it won't start at all when hot
- • Stalling at idle or when you come to a stop, then it restarts fine a minute later
- • Rough, hunting idle with the revs wandering up and down
- • Hesitation or a flat spot under acceleration as the timing loses its reference
- • Tacho needle dropping to zero or jumping about while the engine is still running
Possible causes
Causes commonly associated with P0336, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failing crankshaft sensor, the usual suspect. They get heat-soaked over the years and the signal starts breaking up once warm, which is why so many P0336 cars start fine cold then play up later
- 2. Damaged or chafed wiring near the sensor, common where the loom runs close to the block or exhaust heat. Look for melted insulation and corroded pins in the connector
- 3. Reluctor ring with a chipped or worn tooth, or debris stuck between the teeth. A broken tooth gives the ECU a false reference and throws this code straight away
- 4. Sensor air gap wrong because it isn't seated properly or someone fitted the wrong part, so the signal amplitude is too weak or inconsistent
- 5. Crank end float or a worn crank pulley letting the trigger wheel wobble, which messes with the readings, more common on high-mileage engines
- 6. Poor earth or unstable supply to the sensor, occasionally a dodgy ECU connection, though that one is rare
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read live data and the freeze frame, then note whether the fault appears cold or hot. A code that only sets once the engine warms up points hard at the sensor itself rather than wiring
- 2. Back-probe the sensor connector and check the wiring and pins for corrosion, green crusty terminals, or a loose fit. Wiggle the loom while watching the data if you can
- 3. Put a scope on the sensor output during cranking and running. You want a clean, even waveform with one obvious gap for the reluctor reference. A ragged or dropping-out trace tells you sensor or wiring
- 4. If the waveform shows a glitch in the same spot every revolution, suspect the reluctor ring. Inspect it for a damaged tooth or muck packed between teeth, a borescope helps on engines where the sensor sits behind the bellhousing
- 5. Check the air gap and that the sensor is fully home against its mounting, especially if someone has been in there recently
- 6. Confirm earth integrity and supply voltage at the sensor before you ever blame the ECU. Crank sensor ECU faults are uncommon
Common questions about P0336
If I clear the code, will it stay gone or come straight back? +
If the sensor is on its way out it'll come back, usually once the engine warms up and the failing sensor starts dropping its signal again. You might get a few good starts after clearing it, which fools people into thinking it's fixed. Clearing is fine as a test to confirm it returns, but it isn't a repair. If it stays away for weeks it was probably a one-off poor connection or a bit of debris on the reluctor ring that has cleared itself.
What am I risking if I just leave it and keep driving? +
The main risk is being left stranded. A crank sensor that's breaking up can cut the engine dead with no warning, and if it happens pulling out of a junction or on the motorway that's a real safety issue. You're also likely running on degraded timing, so expect rough running, worse economy, and possible misfire damage over time. It won't blow the engine up, but it will get steadily more unreliable until you can't trust the car to start.
How urgent is this, can it wait a couple of weeks? +
Treat it as soon-ish rather than emergency, but don't ignore it. If the car still starts and runs cleanly most of the time you've got a window to book it in. The moment it starts stalling in traffic or refusing to restart when hot, stop driving it and get it sorted, because that's the sensor telling you it's about to leave you on the hard shoulder. The fix is rarely expensive, the sensor itself is usually a low three-figure job at an independent garage, so there's little reason to drag it out.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →