Cummins X15 CM2350 X116B Performance Series (2018 & Newer) Fault Code: 4251 PID: SPN: 5798 FMI: 10 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Heater Temperature- Abnormal Rate of Change

Circuit Description
The aftertreatment diesel exhaust fluid dosing unit heater is used to defrost and/or prevent freezing of the diesel exhaust fluid dosing unit.

Component Location
The aftertreatment diesel exhaust fluid dosing unit location is original equipment manufacturer (OEM) dependent. Refer to the OEM service manual.

Conditions for Running the Diagnostics
This diagnostic runs when the aftertreatment diesel exhaust fluid dosing unit heater is commanded ON.

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid dosing unit heater temperature sensor reading was not changing when the heater was commanded ON.

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
To validate the repair, perform a key cycle, and then use INSITE™ electronic service tool to perform the Diesel Exhaust Fluid Doser System Heater Test found under ECM Diagnostic Tests.
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 diesel exhaust fluid dosing unit heater
A malfunctioning aftertreatment diesel exhaust fluid dosing unit heater temperature sensor

Possible Cause:
1) OEM harness
2) ECM calibration