Cummins ISB4.5 CM2150 Fault Code: 1694 PID: 2201 SPN: 3226 FMI: 2 Aftertreatment Outlet NOx Sensor – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The aftertreatment outlet mono-nitrogen oxides (NOx) sensor is a smart device that receives commands from the engine 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 single component and can not be replaced individually. The aftertreatment outlet NOx sensor is used to measure the outlet NOx emissions from the engine.

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 SCR catalyst.

Conditions for Running the Diagnostics
This diagnostic runs only under certain engine operating conditions. Refer to the troubleshooting tree for details on running the diagnostic.

Conditions for Setting the Fault Codes
The ECM has detected that the NOx reading is higher or lower than is possible from the engine output.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately after the diagnostic runs and fails on two consecutive ignition cycles.
-Engine torque will be reduced.

Conditions for Clearing the Fault Code
-This fault code can not be cleared with INSITE™ electronic service tool.
-Aftertreatment selective catalytic reduction (SCR) catalyst temperatures must exceed 200°C [392°F].
-The engine must be in a motoring condition (zero fueling and negative torque) for a minimum continuous period of 25 seconds.
-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 a reoccurrence.

Possible Causes
-The ECM has detected that the NOx reading is higher or lower than is possible from the engine output.
-Exhaust system leaks.
-An incorrectly installed aftertreatment outlet NOx sensor.
-An aftertreatment outlet NOx sensor that has carbon buildup on the tip of the sensor.
-Excessive oil consumption.
-Possible engine misfire.
-The NOx sensor part number is incorrect.