What is the difference between P0340 and P0341?

P0340 means the camshaft sensor signal is missing or unusable — nothing is arriving, or what arrives cannot be interpreted at all. P0341 means a signal is arriving perfectly well but the pattern is wrong for where the crankshaft says the engine is. That distinction matters because a missing signal is usually the sensor, the connector or the wiring, while a present-but-wrong signal is what a stretched or jumped timing chain produces. P0341 therefore needs the mechanical timing checking, not just a new sensor.

Can a stretched timing chain cause P0341?

Yes, and it is the leading cause. As a chain stretches, the camshaft it drives falls progressively behind the crankshaft, so the sensor signal keeps arriving but in the wrong place. The clues are a rattle for the first second or two after a cold start, hard starting, and a camshaft-to-crankshaft correlation code such as P0016 stored alongside. Have the timing measured properly before spending anything on sensors, because a chain in that state can skip further and bend valves.

Can I drive with a P0341 code?

Only as far as a garage. The code covers both a failing sensor, which is harmless in itself, and a timing chain on the way out, which can destroy the engine, and nothing about how the car drives will tell you which you have. Any rattle at start-up, hard starting or reduced power mode means recovering it rather than driving it.

Will P0341 fail an MOT?

Yes. An illuminated engine management lamp is a major defect for petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, which is the largest warning-lamp defect in the DVSA data behind this site at 371,859 failures. Because this fault is often intermittent, people are tempted to clear the code before the test, but that also resets the readiness monitors and the tester can see they have not run.

Powertrain code · standard

P0341Camshaft sensor signal is there, but wrong

Standard definition: Camshaft Position Sensor "A" Circuit Range/Performance (Bank 1)

Last updated 27 July 2026

Quick answer

The camshaft sensor is producing a signal, but the pattern does not match what the control unit expects for the crankshaft position it is seeing. That makes P0341 a step more serious than P0340, because a plausible but incorrect signal is exactly what a slipped timing chain produces.

How the car works this out

A range or performance code means the input is present and within its electrical limits but does not make sense. For a camshaft sensor that means the pulses are arriving, just not where they should relative to the crankshaft, or not with the spacing and duration the control unit expects for the engine speed it is seeing. Because the check is about the pattern rather than the presence of a signal, the same code covers two very different worlds: a sensor or trigger wheel that is misreporting, and a timing drive that has genuinely moved. Which one it is cannot be settled by reading the code, only by comparing the actual camshaft and crankshaft timing against the manufacturer's figures.

What you might notice

Rough running that comes and goes, sometimes with no pattern to it
Hesitation, stumbling and reduced power
Longer cranking, or intermittent hard starting
A rattle at cold start if the underlying cause is chain wear
The engine management lamp on, sometimes intermittently

What causes it

Most likely first. A code names the check that failed, not the part that failed it, so more than one of these can produce the same number.

1A stretched timing chain, or one that has jumped a toothCommon
How to check: Listen at a cold start, look for a correlation code such as P0016 stored alongside, and have the actual cam timing checked against the manufacturer's data with the phaser commanded fully off.
2A camshaft phaser moving when it should be locked, from internal wear or a loose centre boltPossible
3A cracked, distorted or contaminated trigger wheel on the camshaftPossible
How to check: Inspect the wheel visually where access allows. Debris packed between the teeth affects the signal exactly like a damaged tooth.
4A sensor beginning to fail, giving a weak or noisy output at particular speeds or temperaturesPossible
How to check: A scope trace comparing camshaft and crankshaft signals will show a ragged or drifting waveform where a multimeter shows nothing wrong at all.
5An air gap that has changed because a mounting bolt has worked loose or a spacer was left out after workPossible
6Corroded or spread connector pins adding resistance and rounding off the signal edgesLess common
7Electrical interference from a failing alternator or a badly earthed aftermarket accessoryLess common

What to do about it

1Have the camshaft and crankshaft timing physically verified against the manufacturer's data. This is the code where that step is worth paying for, because it separates a sensor job from an engine job.
2Check the full code list. A correlation code such as P0016 stored alongside makes the timing chain the leading candidate rather than a possibility.
3Ask for a scope trace of the sensor signals rather than a resistance check. A camshaft sensor can measure correctly and still produce a waveform the control unit cannot work with.
4Do not fit a sensor and assume the job is done if the code returns. A returning P0341 with a clean new sensor is the timing drive telling you something.

Can you keep driving?

Only to a garage

This code sits on the fence between an inexpensive electrical fault and an engine-destroying mechanical one, and the car cannot tell you which side it is on. If there is any rattle at start-up, any hard starting or any limp mode, stop using it and have it recovered. If it is driving normally apart from the lamp, get it looked at promptly rather than waiting for the next service.

Will it fail an MOT?

The lamp fails it outright as a major defect on petrol cars first used from 1 July 2003 and diesels from 1 July 2008. What is particular to this code is that it is often intermittent, and people arrive at the test hoping the lamp has stayed out. It does not work that way: once a fault is confirmed the lamp stays lit until the fault has been absent for a set number of drive cycles, and if you clear it manually you also clear the readiness monitors, which the tester can see have not completed. Either way it is a failure, just on a different line of the certificate.

The light this turns on

Engine management lightThe engine management system has found a fault it cannot correct and has stored a code for it. The car will usually still drive, but an illuminated engine light is an automatic MOT failure on petrol cars first used from 1 July 2003 and diesels from 1 July 2008.

Common questions

What is the difference between P0340 and P0341?: P0340 means the camshaft sensor signal is missing or unusable — nothing is arriving, or what arrives cannot be interpreted at all. P0341 means a signal is arriving perfectly well but the pattern is wrong for where the crankshaft says the engine is. That distinction matters because a missing signal is usually the sensor, the connector or the wiring, while a present-but-wrong signal is what a stretched or jumped timing chain produces. P0341 therefore needs the mechanical timing checking, not just a new sensor.
Can a stretched timing chain cause P0341?: Yes, and it is the leading cause. As a chain stretches, the camshaft it drives falls progressively behind the crankshaft, so the sensor signal keeps arriving but in the wrong place. The clues are a rattle for the first second or two after a cold start, hard starting, and a camshaft-to-crankshaft correlation code such as P0016 stored alongside. Have the timing measured properly before spending anything on sensors, because a chain in that state can skip further and bend valves.
Can I drive with a P0341 code?: Only as far as a garage. The code covers both a failing sensor, which is harmless in itself, and a timing chain on the way out, which can destroy the engine, and nothing about how the car drives will tell you which you have. Any rattle at start-up, hard starting or reduced power mode means recovering it rather than driving it.
Will P0341 fail an MOT?: Yes. An illuminated engine management lamp is a major defect for petrol cars first used on or after 1 July 2003 and diesels from 1 July 2008, which is the largest warning-lamp defect in the DVSA data behind this site at 371,859 failures. Because this fault is often intermittent, people are tempted to clear the code before the test, but that also resets the readiness monitors and the tester can see they have not run.

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