Cummins ISB4.5 CM2150 Fault Code: 3579 PID: SPN: 4376 FMI: 5 Aftertreatment Diesel Exhaust Fluid Return Valve – Current Below Normal or Open Circuit.

Circuit Description
The aftertreatment diesel exhaust fluid return valve is controlled by the aftertreatment diesel exhaust fluid controller. The return valve position determines where diesel exhaust fluid will flow as it exits the dosing unit. When the return valve is activated, the dosing system will purge and return the diesel exhaust fluid in the lines to the tank.

Component Location
The aftertreatment diesel exhaust fluid return valve is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The diesel exhaust fluid controller detects that the diesel exhaust fluid return valve circuit is open.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
-An engine torque derate will be activated.

Conditions for Clearing the Fault Code
-This fault code can not be cleared with INSITE™ electronic service tool.
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE lamp and/or MIL immediately after the diagnostic runs and passes.
-Use INSITE™ electronic service tool to verify the fault code is inactive.
-The inactive fault code will be cleared from the memory after 9600 hours of engine operation without a reoccurrence.

Shop Talk
If this fault is active, the dosing system may not be able to purge, which means there will be diesel exhaust fluid left in the lines. Care must be taken when removing connections. Also, the lines could freeze and become damaged in cold weather if the system is not properly purged.