Circuit DescriptionThe aftertreatment intake NOx (nitrogen oxides) sensor is a smart device and communicates with the engine control module (ECM) via the J1939 data link. The aftertreatment intake NOx sensor performs 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 NOx emissions at the intake of the aftertreatment system.

Component LocationThe aftertreatment intake NOx sensor is mounted on the engine near the turbocharger turbine outlet.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault CodesThis fault code was triggered when the ECM loses J1939 data link communications with the aftertreatment intake NOx sensor.

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.Diesel exhaust fluid injection into the aftertreatment system is disabled.Engine torque will be severely reduced.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 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 amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will extinguish 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:

The aftertreatment intake NOx sensor is not receiving power from the battery supply circuit in the OEM harness. This can be caused by an open circuit in the power supply wire, malfunctioned NOx sensor fuse, or low voltage supplied by the battery.Open return circuit on the aftertreatment intake NOx sensor circuit between the battery circuit aftertreatment intake NOx sensor.Open or short circuit on the J1939 data link circuit between the engine ECM and aftertreatment intake NOx sensor.Intermittent communications between the aftertreatment intake NOx sensor and the primary engine ECM on the J1939 data linkReference 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