P0340: Camshaft Position Sensor A Circuit Malfunction (Bank 1 or Single Sensor)

Common causes

• A failed camshaft position sensor
• Damaged wiring or connector
• A stretched timing chain or slipped timing belt (less common)

Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.

Symptoms

• Hard starting or no start
• Stalling or rough running
• Check engine light

Is it safe to drive?

Not recommended: the engine can stall without warning or fail to restart. If it runs rough or you suspect the timing belt or chain has slipped, don't keep running the engine; have it towed.

How to check it with a scanner

1. Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
2. Inspect the sensor connector and wiring.
3. Check for crank and cam correlation codes, which can point to timing problems.
4. Test the sensor's signal against your vehicle's spec.
5. After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.

A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.

Questions

Related codes

• P0335: Crankshaft position sensor circuit
• P0011: Intake cam timing over-advanced, bank 1
• P0341: Camshaft sensor signal doesn't make sense
• All trouble codes
• How to choose a car diagnostic scanner