Camshaft Position Sensor: Description and Operation

Camshaft Position Sensor (CMP)





Two sensors are located at the rear of the engine, in the cylinder head (one per bank), above the rear cylinders. The sensors are Variable Reluctor Sensor (VRS) type, producing four pulses for every two engine crankshaft revolutions. The sensing element is positioned between 0 and 2mm from the side of the cam gear wheel.

The camshaft timing wheel is a sintered component which has four teeth on it to enable the EMS to detect cylinder identification. The signal is used for:
^ Cylinder recognition
^ Enabling sequential fuel injection
^ Knock control
^ Cylinder identification for diagnostic purposes.

Failure symptoms include:
^ Ignition timing reverting to the base mapping, with no cylinder correction.
^ Active knock control is disabled, along with its diagnostic (Safe ignition map - loss of performance).
^ Quick cam/crank synchronisation on start disabled.