2.2.23. SPN 109, FMI 1, Coolant pressure sensor: Pressure below normal.ΒΆ

Description

The measured coolant pressure is below normal operating range. There is a risk of engine overheat and water pump failure.

Possible causes are:

  • Leak in the coolant circuit.
  • Coolant level is too low.
  • Expansion tank pressure cap is defective.
  • Water pump is defective.
  • The coolant pressure sensor wiring is defective.
  • The coolant pressure sensor is defective.

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates an active fault.

Solution

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

  • Make sure that there is no leak in the coolant circuit.
  • Make sure that the expansion tank and pressure cap are working correctly and the coolant level of the expansion tank is correct.
  • Measure the coolant circuit pressure via external pressure gauge. The system pressure must be above 0,3bar at 80degC coolant temperature.
  • Examine the coolant pressure sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Examine the coolant pressure sensor installation to detect possible mechanical failure.
  • Try operation with another coolant pressure sensor to see if the sensor is defective.