Cummins ISX15 CM2250 (2010-12) Fault Code: 4157 PID: SPN: 3361 FMI: 12 Aftertreatment Diesel Exhaust Fluid Return Valve- Mechanical System Not Responding or Out of Adjustment

Circuit Description
The aftertreatment diesel exhaust fluid dosing unit precisely measures the amount of aftertreatment diesel exhaust fluid to be injected into the aftertreatment system. The aftertreatment diesel exhaust fluid dosing unit has three primary cycles. A priming cycle makes sure that aftertreatment diesel exhaust fluid is available at the aftertreatment diesel exhaust fluid dosing unit. During the dosing cycle, aftertreatment diesel exhaust fluid is being delivered to the aftertreatment dosing valve. A purge cycle occurs when the engine is turned OFF. The purge cycle makes sure that all the aftertreatment diesel exhaust fluid is removed from the diesel exhaust fluid lines and dosing valve.

Component Location
The aftertreatment diesel exhaust fluid dosing unit location is OEM dependent. Refer to the OEM service manual for more information.

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

Conditions for Setting the Fault Codes
The aftertreatment diesel exhaust fluid control unit detects that the aftertreatment diesel exhaust fluid dosing unit did not complete a full purge cycle after two attempts.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE light and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
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 Code
To validate the repair, perform the Aftertreatment Diesel Exhaust Fluid Leak Test using INSITE? electronic service tool and allow the aftertreatment diesel exhaust fluid dosing system to prime and complete a purge cycle.
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 light after the diagnostic runs and passes.
For On Board Diagnostic (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 Talk
Fault Code 4157 is triggered when the aftertreatment diesel exhaust fluid dosing unit has detected an error with the fluid return valve circuit.

Possible causes of this fault code include:

Short circuit to ground in the aftertreatment diesel exhaust fluid dosing unit signal/dosing unit fluid return valve wire
Malfunctioned or malfunctioning diesel exhaust fluid dosing unit
Blocked or restricted diesel exhaust fluid lines
Blocked or restricted diesel exhaust fluid dosing unit supply/return line fittings.
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and data link 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 failure
2) ECM calibration
3) Aftertreatment DEF controller calibration