Camshaft Position Sensor
The Camshaft Position (CMP) sensor is located in a hole in the camshaft carrier and is secured with a screw. The sensor tip protrudes through the 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 reference voltage from the Powertrain Control Module (PCM). Two further connections to the PCM provide ground and signal output. The PCM uses the signal from the CMP sensor and the Crankshaft Position (CKP) sensor to determine current exhaust camshaft position and camshaft adjustment.
If a fault occurs with the CMP sensor, a Diagnostic Trouble Code (DTC) is registered in the PCM. Two types of failure can occur:
- The CMP sensor signal frequency too high.
- Total failure of the CMP sensor signal.
The DTC recorded by the PCM can also relate to a total failure of the CKP sensor signal or CKP sensor signal dynamically implausible. Both possible faults 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.