Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 4281 PID: SPN: 5848 FMI: 2 Aftertreatment 1 SCR Intermediate NH3- Data Erratic, Intermittent, or Incorrect

Circuit Description
The aftertreatment SCR intermediate NH3 (ammonia) sensor is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment intermediate NH3 sensor performs its own internal diagnostics and reports malfunctions back to the primary engine control module using the J1939 data link. The aftertreatment intermediate NH3 sensor is used to measure the ammonia in the aftertreatment system.

Component Location
The aftertreatment SCR intermediate NH3 sensor is located in the middle of the aftetreatment SCR catalyst.

Conditions for Running the Diagnostics
This diagnostic has to meet specific engine and aftertreatment conditions to run and complete.

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the aftertreatment SCR intermediate NH3 sensor reading is not changing.

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.

Conditions for Clearing the Fault Code
It is necessary to use the “Reset All Faults” command in INSITE™ electronic service tool to clear this fault and extinguish the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL).

Shop Talk
Possible causes of this fault code include:

A malfunctioning aftertreatment SCR intermediate NH3 sensor probe

Possible Cause:
1) Aftertreatment DEF dosing valve failure
2) Aftertreatment NH3 sensor probe failure
3) ECM calibration