2.2.186. SPN 4201, FMI 31, Crankshaft speed sensor: Signal missing.

Description

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

Possible causes are:

• The crankshaft 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 camshaft speed sensor signal.

Solution

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

• Examine the crankshaft sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation). Look also for a possible reverse connection.
• Measure the coil resistance of the crankshaft sensor (the engine must be stopped). The normal resistance values are + 20°C is 1120 - 1530 Ohms.
• Examine the crankshaft 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 crankshaft speed sensor to see if the sensor is defective.

See Crankshaft speed sensor for reference.