Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 4521 PID: SPN: 5862 FMI: 2 Aftertreatment 1 SCR Intermediate Gas Temperature Sensor- Data Erratic, Intermittent, or Incorrect

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 when the engine is running and exhaust flow is above a minimum level.

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the aftertreatment SCR intermediate temperature sensor signal was irrational for more than 5 minutes.

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, it may be necessary to operate the vehicle on a chassis dynamometer or to drive the vehicle in order to get the engine load high enough for the diagnostic to run.
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
Possible causes of this fault code include:

A malfunctioning aftertreatment SCR intermediate temperature sensor
A malfunctioning aftertreatment SCR outlet temperature sensor

A malfunctioning aftertreatment SCR outlet temperature sensor

Possible Cause:
1) Aftertreatment Selective Catalytic reduction temperature sensor
2) ECM calibration