Circuit DescriptionThe diesel exhaust fluid dosing unit lines are responsible for transporting diesel exhaust fluid between the dosing unit, dosing valve, and diesel exhaust fluid tank.

Component LocationThere are three diesel exhaust fluid lines. One line is between the dosing unit and dosing valve, and the other two lines are between the dosing unit and diesel exhaust fluid tank. These lines can be partially hidden from view by the SCR system and other vehicle components. Line routing will vary based on aftertreatment architecture and the OEM.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position and dosing is being commanded.

Conditions for Setting the Fault CodesThe diesel exhaust fluid controller has detected a mechanical failure of the dosing input lines, and diesel exhaust fluid is not being delivered to the dosing valve.

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, diesel exhaust fluid dosing must be commanded so that the dosing valve is actuated. This can be done by performing the “Aftertreatment Diesel Exhaust Fluid Doser Pump Override Test” found under “ECM Diagnostic Tests” in INSITE? electronic service tool.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 TalkThis fault indicates that the diesel exhaust fluid dosing unit was able to build pressure, but could not complete the priming cycle. Troubleshoot all other active SCR related faults before this fault.

Possible causes of this fault code are:

Blocked or restricted aftertreatment dosing valveBlocked or restricted aftertreatment dosing valve supply lineReference 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) DEF dosing valve failure3) ECM calibration