Circuit DescriptionThe aftertreatment SCR (selective catalytic reduction) temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment SCR temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment SCR temperature sensor module is used to measure the aftertreatment SCR intermediate temperature and aftertreatment SCR outlet temperature. The temperature probes are permanently attached to the aftertreatment SCR temperature sensor module and can not be replaced individually.

Component LocationThe aftertreatment SCR temperature sensor module is mounted on the aftertreatment SCR catalyst.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the temperature at the SCR catalyst outlet temperature sensor was greater than 650°C [1202°F] for more than 60 seconds.

Action Taken When the Fault Code is ActiveThe ECM illuminates the red STOP ENGINE lamp immediately after 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, perform a key cycle, 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 red STOP ENGINE lamp immediately after 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 TalkThis fault will go inactive immediately after the SCR outlet temperature drops below the warning limit, and will likely be inactive at the time of diagnosis. For these reasons this troubleshooting tree must be used for both active and inactive fault codes.

Possible causes of this fault code include:

Malfunctioning SCR catalystDegraded, diluted, or incorrect diesel exhaust fluidMalfunctioning in-range SCR outlet temperature sensor.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) ECM calibration