3.2.119. SPN 3031, FMI 14, DEF system maximum defrost time exceededΒΆ

Description

The maxium defrost time of the DEF system has been exceeded. The allowed defrost time is defined by an authority.

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.
  • DEF supply module heater is defective
  • DEF hose heater is defective

Reaction in EEM

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

NOTE: The present fault is classified as an emission related fault. Engine power will be reduced after a certain time defined by an authority.

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).
  • Check the supply module heater operation. Supply module front cover should feel warm when heater is active. Measure heater resistance from the supply module connector to check possible open loop.
  • Check the DEF hose heaters operation. Hose should feel warm when heater is active. Measure heater resistance to check possible open loop.
  • Check DEF system heater relay control.

See Tank heating valve for reference. See Supply module for reference. See SCR line heaters for reference.

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.