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 continuously when the keyswtich is ON.

Conditions for Setting the Fault CodesThe aftertreatment diesel exhaust fluid controller detects that the diesel exhaust fluid line heater relay circuit is open.

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.Engine torque will be reduced if the engine is operated for a limited period of time with the fault code active.Engine torque will be severely reduced and vehicle speed will be limited to 8 km [5 mi] per hour after extended engine operation with the fault code active.Conditions for Clearing the Fault CodeTo validate the repair, perform a key cycle. 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 3 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:

Open circuit in the aftertreatment diesel exhaust fluid line heater relay circuitOpen circuit 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 line heater relay supply circuit failure2) ECM calibration