2.2.399. SPN 723, FMI 31, Cam speed sensor: Signal missing.

Description

The ECU has not been able to receive a valid speed signal from the camshaft speed sensor.

Possible causes are:

  • The camshaft speed sensor is defective.
  • The sensor wiring is defective

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates an active fault. Engine power is reduced (Degradation Level 2). The engine starting may take longer than normally, and the running may be poor due to missing/incorrect information for the injection timing control. The engine runs with the crankshaft speed sensor signal.

Solution

First save the error log and then do the procedure that follows:

  • Examine the camshaft sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation). Look for possible reverse connection.
  • Measure the coil resistance of the camshaft sensor (the engine must be stopped). The normal resistance values are + 20°C is 774 - 946 Ohms.
  • Examine the camshaft sensor mounting. The air gap between the sensor tip and the trigger wheel teeth should be 0,5 - 1,2 mm.
  • Test the operation with another camshaft speed sensor to see if the sensor is defective.

See Camshaft speed sensor for reference.