Bosch-Common Rail System – CMP sensor

The CMP signal is required by the PCM to activate the individual fuel injectors according to the injection sequence. The CMP sensor works on the Hall principle. The square-wave signal is used to identify cylinder 1, in conjunction with the CKP signal.

Effects of faults

When the engine is started, the synchronization between the CKP signal and the CMP signal takes place in the PCM.

If synchronization cannot be completed successfully, no injection enable signal is sent by the PCM, and the engine does not start.

If synchronization is successfully completed, the CMP signal is of no further consequence. This means that any potential CMP signal loss while the engine is running has no effect.


From the description above it can be concluded that the CMP sensor has no effect on exhaust emissions in the event of a fault, as the engine cuts out or cannot be started. Therefore, this is a non MIL active component. In the event of a fault, the engine system fault warning lamp is actuated.

Possible diagnostic trouble codes: P0340, P0341, P0344.

07. August 2018 by Ron
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