Lamp:Amber

Reason:The diesel exhaust fluid pressure did not decrease below a threshold after a key off.

Effect:Possible reduced engine performance.

Circuit Description:The 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 Location:There 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 Diagnostics:This diagnostic runs immediately after the keyswitch is turned OFF.

Conditions for Setting the Fault Code:The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid pressure was greater than a threshold.

Action Taken When the Fault Code is Active:1. The ECM illuminates the amber check engine lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.2. Engine torque may be reduced.

Conditions for Clearing the Fault Code:It may be necessary to perform both validations to clear this fault:1. To validate the repair, perform the “aftertreatment diesel exhaust fluid system leak test” found under “ECM diagnostic tests” in the recommended diagnostic tool or equivalent.2. To validate the repair, key OFF for 1 minute, then key ON for 1 minute.3. The fault code status displayed by the recommended diagnostic tool or equivalent will change to inactive immediately after the diagnostic runs and passes.4. The ECM will turn off the amber check engine lamp immediately after the diagnostic runs and passes.5. The “reset all faults” command in the recommended diagnostic tool or equivalent can be used to clear active and inactive faults.

Shop Talk:Possible causes of this fault code include:1. The line heaters are not successfully thawing the frozen diesel exhaust fluid.2. The diesel exhaust fluid return line between the diesel exhaust fluid tank and the dosing valve is kinked or blocked.