Camshaft Position (CMP) Sensor

The function of the camshaft position (CMP) sensor is to detect the position of the camshaft rotor flanks. The signal from the sensor is used by the engine control module (ECM) to determine cam timing.

Each camshaft has five flanks per camshaft revolution. Camshaft position sensor (CMP) uses a pulse wheel on the camshaft consisting of five teeth (one tooth positioned by each flank) to detect the flanks.

The flanks are not symmetric on the camshaft. This allows the control module to determine which flank has been detected and therefore which operating cycle the camshaft is in.

When the operating cycle of the camshaft is established, the control module is able to determine which cylinder should be ignited. In the event of misfire or engine knock, the control module is also able to determine which cylinder is misfiring or knocking. See also: KNOCK SENSOR (KS)  and ENGINE SPEED (RPM) SENSOR .

Data about the position of the camshaft is used during camshaft control (CVVT). See also: CAMSHAFT CONTROL (CVVT) 

The sensor, which is a magnetic resistor with a permanent magnet, is grounded in the control module and supplied with 5 V from the control module. When one of the teeth on the camshaft pulse wheel passes the camshaft position (CMP) sensor, a signal is transmitted to the control module from the camshaft position (CMP) sensor. The signal varies between 0-5 V and is high when a tooth is in contact with the camshaft position (CMP) sensor and low when the tooth leaves the camshaft position (CMP) sensor.

Both the intake camshaft and exhaust camshaft have a camshaft position sensor. Cylinder detection on start up (the operating cycle of each cylinder) is improved by using a camshaft position sensor on the intake camshaft and exhaust camshaft.

The camshaft position (CMP) sensors are located by the camshafts at the rear of the engine.

The engine control module (ECM) can diagnose the camshaft position (CMP) sensors.