Circuit DescriptionThe selective catalytic reduction (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 LocationThe SCR intake temperature sensor is located in the aftertreatment system. It is located between the diesel particulate filter and the SCR catalyst in the exhaust system.

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

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

Action Taken When the Fault Code is ActiveThe 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 CodeTo validate the repair, start the engine and make certain that the SCR intake 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 passesFor On-Board Diagnostics (OBD) engines, the ECM will turn off 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 TalkPossible causes of this fault code include:

Stuck in-range SCR catalyst intake temperature sensor readingHigh resistance in the SCR catalyst intake temperature sensor signal or return linesMalfunctioning 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 failure2) ECM failure