Aftertreatment Outlet NOx Sensor – Data Erratic, Intermittent, or Incorrect
|Fault Code: 1694
Aftertreatment Outlet NOx Sensor – Data Erratic, Intermittent, or Incorrect. An incorrect NOx sensor reading has been detected by the aftertreatment outlet NOx sensor.
Aftertreatment outlet NOx sensor operation will be disabled.
Engine will derate after running 50 hours with the fault code active.
Circuit: Aftertreatment Outlet NOx Sensor Circuit
The aftertreatment outlet nitrogen oxides (NOx) sensor is a smart device and receives commands from the engine electronic control module (ECM) via the J1939 datalink. The aftertreatment outlet NOx sensor performs its own internal diagnostics and reports malfunctions back to the primary ECM using the J1939 datalink. 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.
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 catalyst.
On-Board Diagnostics (OBD) information (Euro 4 Stage 1+ Certified Engines):
- The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- An engine torque derate will be activated after 50 hours of engine operation with the fault code active.
- The ECM turns OFF the malfunction indicator lamp (MIL) after 1 ignition cycle that the diagnostic runs and does not fail. The MIL lamp cannot be cleared using the INSITE™ electronic service tool.
- The fault code will be cleared from memory after 400 days or 9600 hours of engine operation.
The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually.
Possible causes of this fault code include:
- 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.