Diesel Nitrogen Oxide (NOx) Sensors
A High Failure Part That's Required for Emissions Regulations NOx sensors monitor the level of nitrogen oxide being emitted by a diesel vehicle to ensure compliance with emissions regulations. Most engines feature two NOx sensors: an upstream and downstream sensor. Common causes of failure include soot buildup on the sensor, ECU water intrusion, and/or damage to the cable, which will cause the check engine light to illuminate. To provide quali...  more