PACCAR PX-9 CM2350 (2013-17) Fault Code:2878 PID:SID 381 SPN:4097 FMI:7 Aftertreatment Fuel Drain Valve – Mechanical System Not Responding or Out of Adjustment

Reason:
Aftertreatment Fuel Drain Valve – Mechanical System Not Responding Properly or Out of Adjustment. The aftertreatment fuel shutoff drain valve has been detected to be stuck closed.

Effect:
Active aftertreatment diesel particulate filter regeneration will be disabled.

Circuit Description:
The aftertreatment fuel drain valve is used to relieve the fuel pressure in the aftertreatment fuel injector supply line. Before active regeneration of the aftertreatment DPF, a diagnostic test on the system is performed. The aftertreatment fuel injector opens and relieves fuel pressure in the line. The aftertreatment fuel pressure sensor must be reading atmospheric pressure at this point in the test. The aftertreatment fuel drain valve closes. The aftertreatment fuel shutoff valve and aftertreatment fuel injector then close and trap the fuel between the aftertreatment fuel shutoff valve and the aftertreatment fuel injector. The diagnostic checks to make sure the system maintains fuel pressure.

Component Location:
The aftertreatment fuel drain valve is located in the aftertreatment fuel shutoff manifold.

Conditions for Running the Diagnostics:
This diagnostic runs during active regeneration of the aftertreatment diesel particulate filter.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected a stuck closed aftertreatment fuel drain valve when the aftertreatment fuel pressure does not change after the aftertreatment fuel drain valve is commanded open.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
2) Active regeneration of the aftertreatment diesel particulate filter will be disabled unitl the next key cycle.
3) 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 Code:
To validate the repair, perform the INSITE™ electronic service tool Aftertreatment Diesel Particulate Filter Regeneration Test. Once the temperatures in the aftertreatment are warm enough to inject diesel fuel into the exhaust, the diagnostic will run.

1) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
2) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes. The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults.

Shop Talk:
N/A

Possible Causes:
1) A stuck closed aftertreatment fuel drain valve
2) A plugged or restricted fuel drain line