Cummins ISX15 CM2250 (2010-12) Fault Code: 3149 PID: SID 254 SPN: 4363 FMI: 10 Aftertreatment SCR Outlet Temperature Sensor- Abnormal Rate of Change

Circuit Description
The SCR outlet temperature sensor is used by the electronic control module (ECM) to monitor the engine exhaust temperature exiting the SCR catalyst. The ECM monitors the voltage on the signal pin and converts this to a temperature value.

Component Location
The SCR outlet temperature sensor is located in the aftertreatment system. The sensor is located after the SCR catalyst.

Conditions for Running the Diagnostics
This diagnostic will only run during active regeneration of the diesel particulate filter.

Conditions for Setting the Fault Codes
The ECM detects that the SCR catalyst outlet temperature is not changing to match engine operating conditions.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp 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, start the engine and ensure that the SCR outlet temperature is less than 350?C [662?F]. Then perform INSITE? electronic service tool Aftertreatment Diesel Particulate Filter Regeneration Test.
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 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
Possible causes of this fault code include:

Stuck in-range SCR catalyst outlet temperature sensor reading
High resistance in the SCR catalyst outlet temperature sensor signal or return lines
Malfunctioning aftertreatment SCR catalyst temperature sensor interface module.
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink 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 SCR catalyst temperature sensor interface module failure
2) ECM failure