Camshaft (CMP) Sensor

Camshaft (CMP) Sensor

The CMP sensor provides a signal which enables the ECM to determine the position of the camshaft relative to the crankshaft. This allows the ECM to synchronise fuel injection for start and run conditions. The CMP sensor provides an output to pin 16 of the ECM connector C0914. The ECM provides an earth for the sensor on pin 42 of ECM connector C0914.

The CMP sensor is located on the camshaft cover (under the plastic cover) at the opposite end to the camshaft drive and reads off a reluctor on the exhaust camshaft.

The sensor is a hall effect sensor which detects the reluctor mounted on the exhaust camshaft. The sensor receives a battery supply from the main relay. The sensor operates on the principle of a voltage generated when the sensor is exposed to a magnetic flux. This causes a potential difference in voltage as the reluctor passes the sensor which is detected as an digital signal by the ECM.

The reluctor consists of a single 'tooth' design which extends over 180 of the camshaft's rotation, for this reason it is known as a half moon cam wheel.

The half moon cam wheel reluctor enables the ECM to provide sequential fuel injection at start up, but it cannot provide a back-up signal in cases of CKP sensor failure.