Fault codeP0340

SEVERE

Camshaft Position Sensor Circuit Malfunction

What this code means

Camshaft Position Sensor Circuit Malfunction.

P0340 is a generic code: it means the same thing on every make. P0340 belongs to family P03xx — Ignition and misfire. Its page explains how to read a code and groups all its codes by part.

Camshaft position sensor

This sensor reads a target on the camshaft and tells the control unit where each cylinder is in its cycle. Combined with the crankshaft sensor, it lets the control unit fire each injector and spark at the right moment and, on engines with variable valve timing, measure the actual cam position.

Symptoms

Longer starting than usual — the control unit has to wait to recognise the cycle —, jerking, loss of power and sometimes stalling. On many engines the car drives in limp mode without the camshaft sensor, but badly.

Common causes

Faulty camshaft position sensor
Damaged connector or loom, oil wicked into the connector
Loose or damaged camshaft reluctor
Stretched timing chain shifting the signal (see P0016)
Engine oil leaking onto the sensor through its seal

How to diagnose it

Inspect the sensor and its connector: oil is often present and breaks the contact. Measure the supply at the connector, often 5 V or 12 V, and the ground, ignition on.

If the supply is correct, replace the sensor — usually a cheap, accessible part. If the code returns, compare crankshaft and camshaft signals to check the timing.

Watch it live in Klaro

With an OBD2 adapter plugged in, these live readings show the part at work, when your car reports them:

Engine RPM
Timing advance

What to do

Have it checked promptly. A misfire sends unburnt fuel into the exhaust and destroys the catalytic converter within a few dozen kilometres. If the light is flashing, stop driving.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →