Circuit DescriptionThe aftertreatment intake NOx sensor is a smart device that receives commands from the engine control module (ECM) via the J1939 data link. The aftertreatment intake NOx sensor performs its own internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually. The aftertreatment intake NOx sensor is used to measure the engine-out NOx emissions.
Component LocationThe aftertreatment intake NOx sensor is mounted on the engine near the turbocharger turbine outlet.
Conditions for Running the DiagnosticsThis diagnostic runs when the diesel oxidation catalyst (DOC) intake temperature at the aftertreatment intake NOx sensor is above 200?C [392?F] and the engine is operating.
Conditions for Setting the Fault CodesThe ECM has detected that the NOx reading is higher or lower than what is expected for the engine operating conditions.
Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.Conditions for Clearing the Fault CodeTo validate the repair, it may be necessary to operate the vehicle on a chassis dynamometer or to drive the vehicle in order to get the engine load high enough for the diagnostic to run.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 TalkPossible causes of this fault code include:
The ECM has detected that the NOx reading is higher or lower than is possible from the engine outputExhaust system leaksAn incorrectly installed aftertreatment intake NOx sensorAn aftertreatment intake NOx sensor that has carbon buildup on the tip of the sensorExcessive oil consumptionPossible engine misfireThe NOx sensor part number is incorrect.Reference the appropriate original equipment manufacturer (OEM) wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.
For intermittent power supply and data link 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 intake NOx Sensor failure2) ECM calibration