Camshaft Position (CMP) Sensor

The camshaft position (CMP) sensor is a hall effect switching device used to determine the position of the bank 2 exhaust camshaft. The CMP sensor detects a single tooth on the reluctor wheel of the camshaft, which denotes 90 degrees before top dead center cylinder 1 compression stroke. The sensor is used by the ECM to determine when cylinder 1 is approaching top dead center necessary to synchronize the correct firing order. The CMP sensor is also used to enable sequential or independent fuel injection and to enable spark knock control.

As the reluctor wheel tooth rotates past the sensor, the sensors internal hall effect device pulls the signal circuit to ground. Therefore, the ECM expects to see one high (5 volts) to low (0 volts) voltage transition once every 2 crankshaft rotations as the reluctor tooth passes the sensor. The signal circuit should be at 5 volts at all times except when the transition occurs. If an error occurs in the CMP sensor circuit during the drive cycle, the ECM will continue to supply fuel and spark to the correct cylinder at the correct time until the ignition is turned OFF. If an error occurs in the CMP sensor circuit upon key-up, then the engine is started, the ECM will default to supplying spark to both mating cylinders and enter non-sequential fuel injection. The engine may experience a 2-3 second extended crank, however, the engine will start and run.