Circuit DescriptionThe aftertreatment diesel exhaust fluid (DEF) dosing valve is controlled by the ECM. When the engine control module (ECM) commands DEF dosing, the ECM sends a pulse width modulated (PWM) signal to the dosing valve, which opens the dosing valve and allows DEF to be sprayed into the exhaust stream.

Component LocationThe aftertreatment diesel exhaust fluid dosing valve is installed in the exhaust system. It is mounted directly to the aftertreatment decomposition tube, before the selective catalytic reduction (SCR) catalyst. Installation position will vary, based on the aftertreatment architecture and the original equipment manufacturer (OEM).

Conditions for Running the DiagnosticsThis diagnostic runs when the diesel exhaust fluid dosing valve is being commanded on.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid dosing valve is mechanically stuck.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

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 the “Aftertreatment Diesel Exhaust Fluid Doser Pump Override Test” found under “ECM Diagnostic Tests” in the INSITE™ electronic service toolThe 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 code include:

A malfunctioning aftertreatment diesel exhaust fluid dosing valveContamination of the DEF can be a possible cause for this fault code.

Possible Cause:1) OEM harness2) Aftertreatment DEF dosing valve failure3) Aftertreatment DEF dosing unit4) ECM calibration