P0012 GMC A Camshaft Position Timing Over Retarded Bank 1
– Faulty camshaft actuator
– Low engine oil level
– Camshaft actuator harness is open or shorted
– Camshaft actuator circuit poor electrical connection
– Possible Lack/Loss of power
– Possible Engine rough idle
Engine Management Systems (EMS) use the camshaft position sensor to manage sequential fuel injection and as part of misfire diagnosis. The EMS constantly monitors the number of pulses on the signal circuit. The EMS compares the number of camshaft sensor reference pulses and the number of crankshaft position sensor reference pulses received. If the EMS receives an incorrect number of pulses, Diagnostic Trouble Codes (DTC) should be stored in the EMS. Some engine management systems will then default to multi-port or “gang-fire” injector operation. The camshaft position sensor signal is required to sequence the injector operation to the proper cylinder timing. If the camshaft position sensor or circuit is faulty most engines will start.