Camshaft Position (CMP) Sensors

Two CMP sensors are used; one for the inlet camshaft and one for exhaust camshaft. The sensors are located on the top of the camshaft cover and are each sealed with an O ring seal and secured with a bolt to the cover.

The sensors are Hall effect sensors which read off a target on each camshaft. Each sensor receives a 5V reference voltage from the ECM. Two further connections to the ECM provide ground and signal output. The ECM uses the signals from the CMP sensors and the CKP sensor to determine current camshaft position and camshaft adjustment.

If a fault occurs with one or both CMP sensors, a DTC (diagnostic trouble code) is registered in the ECM. Two types of failure can occur; camshaft signal frequency too high or total failure of the camshaft signal. The DTC recorded by the ECM can also relate to a total failure of the crankshaft signal or crankshaft signal dynamically implausible. Both components should be checked to determine the cause of the fault.

If a fault occurs with a CMP sensor when the engine is running, the engine will continue to run. Once the engine is switched off, the engine will crank and restart while the fault is present, but VCT control will be disabled.