Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 4166 PID: SPN: 5743 FMI: 16 Aftertreatment Selective Catalytic Reduction Temperature Sensor Module- Data Valid But Above Normal Operating Range- Moderately Severe Level - EcuForce Truck (2024)

Circuit Description
The aftertreatment SCR (selective catalytic reduction) temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment SCR temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment SCR temperature sensor module is used to measure the aftertreatment SCR intermediate temperature and aftertreatment SCR outlet temperature. The temperature probes are permanently attached to the aftertreatment SCR temperature sensor module and can not be replaced individually.

Component Location
The aftertreatment SCR temperature sensor module is mounted on the aftertreatment SCR catalyst.

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

Conditions for Setting the Fault Codes
The aftertreatment SCR temperature sensor module reported the internal circuit board temperature was too high.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

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 a key cycle, start the engine and let it idle for 1 minute.
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 immediately after the diagnostic runs and passes.
For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (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
This fault code indicates the internal temperature of the aftertreatment SCR temperature sensor module was too high. Troubleshoot the exhaust system for leaks, missing heat shields, or dirt and debris that could lead to overheating of the aftertreatment SCR temperature sensor module.

Possible Cause:
1) Aftertreatment SCR temperature sensor module
2) ECM calibration

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