Circuit DescriptionThe aftertreatment diesel exhaust fluid line heaters are used to defrost and/or prevent freezing of the diesel exhaust fluid lines.

Component LocationThe aftertreatment diesel exhaust fluid line heater 2 is located on the return line between the diesel exhaust fluid dosing unit and diesel exhaust fluid tank.

Conditions for Running the DiagnosticsThis diagnostic runs when the keyswitch is in the ON position and line heating is commanded ON.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected an open in the line heater circuit.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.Diesel exhaust fluid injection into the aftertreatment system is disabled.Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.Engine torque will be severely reduced.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, and then use INSITE™ electronic service tool to perform the Diesel Exhaust Fluid Doser System Heater Test found under ECM Diagnostic Tests.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 immediately after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (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 include:

Malfunctioning line heater relayMalfunctioning line heaterAn open circuit in the OEM harnessReference 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) OEM harness2) ECM calibration