Circuit DescriptionThe aftertreatment DEF dosing unit reports its internal temperature to the DEF controller via the dosing unit SIGNAL wire. The DEF controller communicates this information to the primary engine control module (ECM) via the J1939 data link network.

Component LocationThe aftertreatment DEF dosing unit location is original equipment manufacturer (OEM) dependent. Refer to the OEM service manual for a detailed component location view.

Conditions for Running the DiagnosticsThis diagnostic runs immediately after the keyswitch is turned to the ON position, and continues until the DEF dosing unit attempts to prime.

Conditions for Setting the Fault CodesThe aftertreatment DEF dosing unit internal temperature was not communicated to the ECM by the DEF controller, or the dosing unit temperature reading is erratic.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately after the diagnostic runs and fails for two consecutive trips.DEF 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 code active.Conditions for Clearing the Fault CodeStart the engine and let it idle. If, after the engine idles for 10 minutes, the fault code is still not active, the repair has been validated.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 circuit across pins in the aftertreatment DEF dosing unit harness.Malfunctioning dosing unitShort circuit to ground in the aftertreatment DEF dosing unit SIGNAL/dosing unit temperature wire.Aftertreatment DEF controller calibration is not the latest versionReference 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) Aftertreatment DEF controller Harness3) ECM calibration