Circuit DescriptionThe diesel exhaust fluid dosing unit monitors its internal temperature and reports it back to the diesel exhaust fluid controller at initial key ON via the aftertreatment diesel exhaust fluid dosing unit signal/dosing unit temperature wire. After the temperature message has been sent from the dosing unit to the controller, this shared wire is switched over to be used for dosing unit pump control.

Component LocationThe aftertreatment diesel exhaust fluid dosing unit location is OEM dependent. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs at initial key-ON.

Conditions for Setting the Fault CodesThe diesel exhaust fluid dosing unit and the diesel exhaust fluid controller are not able to acknowledge each other at key ON, and can not initialize.

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.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 or open circuit in the aftertreatment wiring harnessMalfunctioning diesel exhaust fluid dosing unit.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