Circuit DescriptionThe diesel exhaust fluid dosing unit input 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 the 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 the aftertreatment architecture and the OEM.

Conditions for Running the DiagnosticsThis diagnostic runs when the SCR system is trying to prime.

Conditions for Setting the Fault CodesThe aftertreatment diesel exhaust fluid dosing unit has been unable to successfully prime after multiple attempts.

Action Taken When the Fault Code is ActiveThere are two levels of action taken by the ECM when this fault code is active:

Level 1: Action taken immediately after the diagnostic runs and fails.

The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL)Diesel exhaust fluid injection into the aftertreatment system is disabledEngine torque will be severely reduced.Level 2: Action taken when diesel exhaust fluid dosing unit has been unable to prime and engine shutdown or extended idle.

The ECM illuminates the amber CHECK ENGINE light and/or the MILDiesel exhaust fluid injection into the aftertreatment system is disabledEngine torque will be severely reducedVehicle speed will be limited to 8 km [5 mi] per hour.Conditions for Clearing the Fault CodeTo validate the repair, use INSITE? to perform the “Diesel Exhaust Fluid Doser Override Test” under the “ECM Diagnostics Test” menu.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 Diagnostics (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 unable to successfully build pressure or prime after multiple attempts. If Fault Code 3612 is also stored in the ECM, the dosing unit may have failed to purge on multiple occasions, and dosing unit damage may have occurred. Troubleshoot Fault Code 3612 after this fault code has been resolved.

Possible causes of this fault code include:

Low aftertreatment diesel exhaust fluid level in the diesel exhaust fluid tankThe line heaters are not successfully thawing the frozen diesel exhaust fluidThe diesel exhaust fluid pressure line between the dosing unit and dosing valve is kinked, broken, or disconnectedThe diesel exhaust fluid suction line between the diesel exhaust fluid tank and the dosing unit is kinked, broken, or disconnectedMalfunctioning diesel exhaust fluid dosing unitThe diesel exhaust fluid suction and return lines between the dosing unit and diesel exhaust fluid tank are reversedDebris from the diesel exhaust fluid tank. If debris is found in the diesel exhaust fluid tank, clean the diesel exhaust fluid tank thoroughly and fill with certified diesel exhaust fluid.Aftertreatment diesel exhaust fluid dosing unit was not allowed to shut down and purge fully following a recalibration of the ECM. A full key cycle that allows the dosing unit to purge, followed by a priming cycle, should rectify this issue. A calibration change found in aftertreatment diesel exhaust fluid controller software version 3.7.8 was developed to prevent future occurrences of this situation.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 dosing Unit Intake fitting failure2) DEF tank filter, DEF tank vent filter, and DEF suction line failure3) DEF dosing unit intake and backflow fitting failure4) Aftertreatment DEF dosing unit failure5) ECM calibration