4.2.161. SPN 4357, FMI 4, DEF pressure line heater relay high side (heater, main relay) open circuitΒΆ

Description

EEM4 monitoring system has detected open circuit on DEF pressure line heater relay.

Possible causes are:

  • The DEF pressure line heater relay wiring is defective.
  • The DEF pressure line heater relay 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 clear it. After clearing, restart the ECU. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the DEF pressure line heater relay wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Measure cable from DEF supply module heater to ECU to detect faulty cable.
  • Check the operation with another heater relay (main relay) to see if relay is defective.