Cummins ISB4.5 CM2150 Fault Code: 3143 PID: SPN: 3143 FMI: 4 Aftertreatment SCR Intake Temperature Sensor Circuit – Voltage Below Normal or Shorted to Low Source.

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

Component Location
The SCR intake temperature sensor is located in the exhaust aftertreatment system. It is located between the turbocharger outlet and the intake of the SCR catalyst in the exhaust system.

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 intake temperature sensor signal voltage is below a calibratible value when the keyswitch is in the ON position.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the MIL immediately after the diagnostic runs and fails.
-Engine torque will be reduced.
-A default value for the aftertreatment SCR intake temperature is used.

Conditions for Clearing the Fault Code
-This fault code can not be cleared with INSITE™ electronic service tool.
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE lamp and/or MIL immediately after the diagnostic runs and passes.
-Use INSITE™ electronic service tool to verify the fault code is inactive.
-The inactive fault code will be cleared from the memory after 9600 hours of engine operation without a reoccurrence.

Shop Talk
The SCR intake 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
-Signal shorted to ground in the harness
-Signal shorted to return or ground in the sensor.