Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
The camshaft sensor tells the engine computer which stage of its cycle each cylinder is in; it uses it together with the crankshaft sensor to time injection and ignition.
What the car has detected
The camshaft sensor signal (usually the bank 1 intake one) is missing or wrong, or the circuit is open, shorted to earth or shorted to voltage.
Often the engine keeps running thanks to the crankshaft sensor, but it may start worse, lack power or, in some cases, not start. Get it checked soon.
Symptoms
- Engine warning light on
- Longer or harder starting
- Loss of power or limp mode
- Hesitation or rough idle
Possible causes
- Failed camshaft sensor
- Damaged wiring or connector (open or shorted circuit)
- Timing out of adjustment (chain or belt)
- Engine computer fault (rare)
Checks for the garage
- Check the battery and charging voltage
- Check the sensor connector and wiring
- Measure the sensor's supply (usually 5 V) and earth
- With the engine idling, check with diagnostics that the camshaft signal arrives and is steady
- Check the timing if the circuit is fine
Next step
Have the camshaft sensor, its connector and wiring checked, and the timing verified.
Go to a garage if the code comes back or the car starts badly. Electrical and timing checks need diagnostics.