Cummins ISB4.5 CM2150 Fault Code: 3681 PID: 411 SPN: 3228 FMI: 0 Aftertreatment outlet NOx sensor power supply – Data erratic, intermittent, or incorrect.

Circuit Description
The aftertreatment outlet NOx (nitrogen oxides) sensor is a smart device and receives commands from the engine electronic control module (ECM) via the J1939 data link. The aftertreatment outlet 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 outlet NOx sensor is used to measure the NOx emissions at the outlet of the aftertreatment system.

Component Location
The aftertreatment outlet NOx sensor location can vary, depending on engine application. It is usually located in the exhaust system at the outlet of the aftertreatment SCR catalyst.

Conditions for Running the Diagnostics
This diagnostic runs when the exhasut gas temperature at the aftertreatment outlet NOx sensor is above 150°C [302°F].

Conditions for Setting the Fault Codes
The ECM has detected that the power supply to the outlet NOx sensor is above or below a threshold.

Action Taken When the Fault Code is Active
-The 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 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 10 minutes to allow the NOx sensor to warm up.
-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 an occurrence again.

Possible Causes
-Short to battery or ground in the OEM harness
-Internal malfunction of the outlet NOx sensor