Camshaft Position (CMP) Sensor
The CMP sensor is located in a hole in the camshaft carrier and is secured with a screw. The sensor tip protrudes through camshaft carrier to pick up on a reluctor ring on the exhaust camshaft. The CMP sensor is a Hall effect sensor which produces a square wave signal, the frequency of which is proportional to engine speed. The sensor measures the magnetic field variation induced by the reluctor ring.
The CMP sensor receives a 5V reference voltage from the PCM. Two further connections to the PCM provide ground and signal output. The PCM uses the signal from the CMP sensor and the CKP sensor to determine current exhaust camshaft position and camshaft adjustment.
If a fault occurs with the CMP sensor, a DTC is registered in the PCM. Two types of failure can occur; camshaft signal frequency too high or total failure of the camshaft signal. The DTC recorded by the PCM 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 the 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 Variable Camshaft Timing (VCT) control will be disabled.