Circuit DescriptionThe aftertreatment diesel exhaust fluid line heater relay provides the power supply to line heaters 1, 2, and 3. It is controlled by the aftertreatment diesel exhaust fluid controller.

Component LocationThe aftertreatment diesel exhaust fluid line heater relay location is original equipment manufacturer (OEM) dependent. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs at key OFF. The fault will be active at the next key-ON event.

Conditions for Setting the Fault CodesThe aftreatment diesel exhaust fluid controller detects that the voltage in the diesel exhaust fluid line heater relay circuit is below a calibratible value.

Action Taken When the Fault Code is ActiveThe electronic control module (ECM) illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.Conditions for Clearing the Fault CodeTo validate the repair, perform a key cycle, and then start the engine and let it idle for 1 minute.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostic (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications

Shop TalkPossible causes of this fault code include:

Short to ground in the aftertreatment diesel exhaust fluid line heater relay circuitShort to ground in the aftertreatment diesel exhaust fluid controller harnessMalfunctioning aftertreatment diesel exhaust fluid controller.Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Cause:1) Aftertreatment DEF controller harness failure2) ECM calibration