Circuit DescriptionThe aftertreatment DEF dosing unit reports its internal temperature to the diesel exhaust fluid 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 component location information.

Conditions for Running the DiagnosticsThis diagnostic runs immediately after the keyswitch is turned to the ON position, and continues until the diesel exhaust fluid 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.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 code active.Conditions for Clearing the Fault CodeAfter making the repair, use the “Reset All Faults” command in INSITE? electronic service tool to clear active and inactive faults.Start 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.

Shop TalkPossible causes of this fault code include:

Malfunctioning dosing unitShort circuit to ground in the aftertreatment DEF dosing unit SIGNAL/dosing unit temperature wireAftertreatment DEF controller calibration is not the lastest version.

Possible Cause:1) Aftertreatment DEF controller calibration2) OEM harness3) Aftertreatment DEF controller harness failure4) ECM calibration