Cummins ISX15 CM2250 (2010-12) Fault Code: 3146 PID: SPN: 3146 FMI: 3 Aftertreatment SCR Outlet Temperature Sensor Circuit- Voltage Above Normal or Shorted to High Source

Circuit Description
The selective catalytic reduction (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. It is located after the SCR catalyst.

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

Conditions for Setting the Fault Codes
The ECM detects that the SCR catalyst outlet temperature sensor signal voltage is higher than 4.4-VDC for more than 2 seconds.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) 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 a limited period of time with the fault code active.
Engine torque will be severely reduced and vehicle speed will be limited to 8 km [5 mi] per hour after extended engine operation with the fault code active.
Conditions for Clearing the Fault Code
To validate the repair, 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 after the diagnostic runs and passes.
For On-Board Diagnostics (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
The SCR outlet temperature sensor shares return wires in the engine harness with other sensors. A shorted return can cause multiple fault codes to be active.

Possible causes of this fault code include:

Open return circuit in the harness, connectors, or sensor
Open signal circuit or shorted to a voltage source
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
3) Engine Harness, OEM harness failure