P0344
PowertrainCamshaft Position Sensor "A" Circuit Intermittent
The ECU watches the pulse pattern coming off the camshaft position sensor on bank 1, and when that signal drops out or goes erratic for a moment then comes back, it logs P0344. The key word here is intermittent. The sensor isn't dead, it's misbehaving now and then, which is why your car might run fine for a week and then stall at a junction. That on-off nature makes this one of the more frustrating faults to pin down, because the car often behaves perfectly the moment it lands on the ramp.
ⓘ Information only. This page provides general educational information about fault code P0344. 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 P0344 mean?
P0344 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Camshaft Position Sensor "A" Circuit Intermittent.
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 coming and going rather than staying on solid
- • Rough or hunting idle, typically wandering around the 600-900 rpm mark
- • Hard starting, worse from cold when the engine is sitting overnight
- • A momentary stall or cut-out at idle or low speed, often with no warning
- • Hesitation or a flat spot when you pull away, mostly low to mid revs
- • Occasional brief loss of power as the engine drops into a fail-safe mode then recovers
Possible causes
Causes commonly associated with P0344, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. The camshaft sensor itself breaking down when it heats up or cops moisture inside, by far the most common cause and worse on older sensors that have done high miles
- 2. Corroded, chafed, or loose wiring at the sensor connector, common where the harness runs near hot or vibrating parts
- 3. A poor earth or a connector pin that has backed out slightly, giving an intermittent open circuit
- 4. Sensor mounting or air-gap wrong after a previous repair, so the tone wheel passes too far from the pickup
- 5. A worn or stretched timing chain letting the cam move erratically, which the sensor faithfully reports as a wobbly signal. Common on certain VAG and BMW chain-driven engines at higher mileage
- 6. Electrical noise from a failing alternator or a dodgy injector earth upsetting the signal
- 7. ECM fault or out-of-date software, rare, and only after everything else checks out
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 freeze-frame for P0344 so you know what the engine was doing when it dropped the signal. Cold start, idle, or under load tells you a lot about where to look
- 2. Wiggle-test the sensor connector and harness with the engine running and the scanner watching the cam signal. If the signal glitches when you flex the loom, you've found it. This is the highest-yield check on an intermittent fault
- 3. Inspect the connector and pins closely for green corrosion, spread terminals, or a backed-out pin, and check the sensor's earth
- 4. Back-probe the signal wire and watch the voltage at idle and on a cold start. A healthy sensor usually swings cleanly within roughly 0.5-5V; dropouts or flat spots point at the sensor or its feed
- 5. Check continuity from the sensor terminal back to the ECM pin, looking for high resistance on the signal line rather than a dead short
- 6. If wiring and sensor both test clean, look at timing chain wear and tension, then last of all check for an ECM software update
Common questions about P0344
Will my car fail the MOT with a P0344 stored? +
The code on its own doesn't fail you, but if the engine warning light is glowing when the tester looks at the dash, that's a fail for the MIL. Sort the actual fault, then drive a few proper journeys to let the light go out before you book the test. If the light keeps coming back on, the underlying problem isn't fixed yet.
What's this likely to cost me to put right? +
If it turns out to be the sensor, you're looking at roughly £80 to £180 fitted at a good independent garage, with the part often £20 to £70 on common engines. A main dealer will charge more, frequently £200 plus. Wiring repairs land in a similar range depending on how buried the loom is. If a diagnosis points at a stretched timing chain, that's a different conversation entirely and can run well into four figures on a chain-driven petrol.
How do I know whether it's the sensor or the wiring on my car? +
The wiggle test settles it most of the time. Get the cam signal up on a scanner and flex the connector and harness by hand. If the trace glitches as you move the loom, your problem is wiring or a tired connector, not the sensor. If the signal stays clean while you waggle everything but still drops out randomly when hot, the sensor itself is the prime suspect. Sensors that fail intermittently almost always get worse with heat, so a fault that shows up after twenty minutes of driving leans towards a dying sensor.
Can I just replace the sensor myself and be done with it? +
On a lot of engines, yes. The cam sensor is usually a one or two bolt job on the cylinder head or timing cover, you unplug it, swap it, and clear the code. Buy a decent branded sensor rather than the cheapest one going, because budget cam sensors are a known source of repeat intermittent faults. What you can't safely DIY is the wiring chase or the timing chain assessment, so if a new sensor doesn't cure it, stop and get it scoped before you spend more money.
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 →