P0340: Camshaft Position Sensor "A" Circuit (Bank 1 Or Single Sensor)
The engine control unit is not receiving a valid camshaft position signal.
Normal risk
Usually drivable, but starting may take longer. Have it checked soon.
Short answer · Can I keep driving with P0340?
Usually yes. Many engines run on the crankshaft signal alone, but starting can take longer and the engine may stall. Have it checked soon.
What does P0340 mean?
The camshaft position sensor identifies which cylinder is on its compression stroke. Code P0340 means the signal from sensor A on bank 1 (or the only sensor) is missing or out of range.
Oil in the connector from a leaking cam cover gasket and damaged trigger wheels are common reasons, as is a timing problem.
Swapping sensors between banks on V-engines can help confirm a faulty sensor.
What the car does when the code is set
The check engine light comes on. Most engines keep running using the crankshaft signal, but starting may take longer, and the variable valve timing may be switched off, which reduces power.
How the system works
The camshaft turns at half the crankshaft speed, so the crankshaft signal alone cannot tell whether a piston at top dead centre is on its compression or exhaust stroke. The camshaft position sensor reads a trigger wheel on the camshaft and gives that information. The engine control unit uses it for sequential injection, ignition on some engines and variable valve timing control. Many engines can still run without it after a few revolutions, but starting may take longer.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Faulty camshaft position sensorThe sensor fails or gives an irregular signal.
- Wiring or connector faultOil leaks from the cam cover often reach the connector.
- Timing problemA stretched chain or jumped belt changes the signal timing.
- Damaged trigger wheelBent or broken teeth on the camshaft trigger.
How it is diagnosed
- Check the connectorLook for oil in the connector and damaged pins.
- Check the sensor signalCheck supply, ground and signal as in the service data.
- Check for related codesCombined with crankshaft-camshaft correlation codes, the timing should be checked.
- Replace and clearAfter replacing the sensor, clear the code and check the engine starts normally.
Questions about P0340
Can a new sensor solve the problem?
Only if the sensor is faulty. Check wiring, connector and timing too.
Can I drive with a camshaft sensor code?
Usually yes, but the engine may be harder to start and use more fuel. Have it fixed soon.
Why do I need a timing check?
If both camshaft and crankshaft sensors are fine but codes persist, the timing itself may have shifted.