NOx Sensor

What reset or learning steps are required after replacing a NOx sensor?
1. Clear fault codes and perform a system reset
After replacing a sensor, first use a professional diagnostic tool to read and clear the existing NOx sensor fault codes to ensure the ECU can receive the new sensor's signal.

2. Perform the sensor calibration (learning) procedure
Use the diagnostic tool to access the calibration menu of the emission control system and perform "sensor learning" or "adaptation" according to the manufacturer's instructions. This will allow the ECU to quickly establish a baseline NOx concentration under different operating conditions.

3. Conduct a road test to verify
After completing the reset and learning process, conduct a road test of at least 10 km to monitor exhaust NOx data for stability and confirm that the sensor response time (<1400ms) meets specifications.

4. Recheck the electrical connections
After the road test, recheck the tightness of the sensor connector, wiring harness, and heater circuit to prevent loosening caused by vibration from triggering the fault again.
Why does carbon deposits/soot cause NOx sensor failure? 1. Probe Surface Contamination
After long-term operation, carbon residue and soot in the exhaust gas can deposit on the sensor probe surface, preventing direct gas contact with the sensor element and causing signal attenuation or distortion.

2. Intake Passage Blockage
Carbon deposits can block the sensor's air inlet, reducing airflow and increasing sensor response time, even leading to zero readings.

3. Chemical Corrosion and Electrode Aging
Sulfides and metal particles contained in soot can corrode the electrodes of electrochemical NOx sensors, accelerating component aging and leading to sensor failure.

4. Poor Heat Dissipation
The carbon layer can reduce the sensor's heat dissipation efficiency, causing the operating temperature to rise abnormally, further accelerating the aging and failure of the sensor's internal materials.