Camshaft Position (CMP) Sensor

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The CMP sensor detects the position of the camshaft. The CMP sensor identifies when piston number 1 is on its compression stroke. A signal is then sent to the PCM and used for synchronizing the sequential firing of the fuel injectors. Coil on plug (COP) ignition applications use the CMP signal to select the correct ignition coil to fire.

Engines with 2 camshafts and with variable camshaft timing (VCT) are equipped with 2 CMP sensors. The second sensor identifies the position of the camshaft on bank 2. Engines with 4 camshafts and with variable camshaft timing (VCT) are equipped with 4 CMP sensors. The 4 sensors identify the position of each camshaft.

The 4 sensor system uses the following CMP signal circuit names:

CMP11 - bank 1, intake camshaft
CMP12 - bank 1, exhaust camshaft
CMP21 - bank 2, intake camshaft
CMP22 - bank 2, exhaust camshaft

There are the 2 types of CMP sensors used. The 2 pin variable reluctance sensor and the 3 pin Hall effect sensor.

Fig 1: Identifying Typical Variable Reluctance CMP Sensor

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Typical Hall Effect CMP Sensor

Courtesy of FORD MOTOR CO.