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Home >> Land Rover >> 2002 >> Range Rover >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Computerized Engine Controls >> Input Devices >> Camshaft Position (CMP) Sensor

Camshaft Position (CMP) Sensor

NOTE: It is physically possible to interchange camshaft gear wheel between pre 1999 year models with GEMS systems and post 1999 year models with Bosch Motronic systems. Because GEMS and Bosch Motronic systems are incompatible, an incorrect camshaft signal will be received by the ECM and a P0340 DTC will set.

  1. Discovery & Range Rover

    CMP sensor is a Hall Effect sensor located in the engine front cover. CMP sensor produces 4 pulses for every 2 revolutions of the engine (one pulse is slightly longer than the others). CMP sensor signals are generated from 4 gaps on cam gear (one gap is smaller than the others). CMP sensor signals are used by ECM to correct fuel injector timing for fully sequential operation, active knock control, and diagnostic purposes.

    If CMP sensor fails, default strategy is to continue normal ignition timing. Fuel injectors will be actuated sequentially based on top dead center timing. Injection timing will either be correct or one revolution (360 degrees) out of synchronization. A fault is indicated by illumination of the MIL.

  2. Freelander

    The CMP sensor provides a signal which enables the ECM to determine camshaft position relative to the crankshaft. This enables the ECM to synchronize fuel injection for start and run conditions. The CMP sensor is located on the left (front) camshaft cover, at the opposite end to camshaft drive, in line with a "half moon" reluctor on the exhaust camshaft. The reluctor comprises a single tooth which extends around 180 degrees of the camshaft circumference. The CMP sensor operates using the Hall effect principle. A permanent magnet inside the sensor applies a magnetic flux to a semiconductor, which receives a power supply from the main relay. The output voltage from the semiconductor is sent to the ECM. As the gap in the reluctor passes the sensor tip, the magnetic flux is interrupted, causing a fluctuation of the output voltage, producing a digital signal. If the CMP sensor fails during engine operation, the engine will continue to run until turned off. The engine will not restart until faulty CMP sensor input is restored.
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