3.2.117. SPN 3031, FMI 10, DEF tank temperature abnormal rate of change at heating cycleΒΆ

Description

The DEF tank temperature is monitored by the EEM4 engine control. If the tank heating request is enabled but the temperature has not changed during the heating cycle, then the fault code will be released.

Possible causes are:

  • The coolant flow of the tank heating element is prevented.
  • The DEF tank temp. sensor wiring is defective.
  • The DEF tank temp. sensor is defective.

Reaction in EEM

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

Solution

First save the error log and then erase it. Restart the ECU after erasing the error log. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the coolant circulation of the tank heating element; The hoses from the engine to the heating element and back.
  • Check the operation with another tank heating valve to see if the valve is defective.
  • Check the DEF tank temp. sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).

NOTE: The DEF tank temp. and level sensors have a common reference GND.

  • Check the operation with another tank temperature/level sensor to see if the tank temperature/level is defective.