Nissan Cima NOx Sensor Fault

Hey there! NOx sensors are a pain. Exhaust leaks near the sensor could definitely throw things off, causing the check engine light. Because the engine control unit monitors the air-fuel ratio based on the sensor's input, a leak could impact the values. Have you tried wiggling the cable while the engine runs to see if the fault code changes, or if the rough idling gets better or worse?

Thanks for the suggestion. I did try wiggling the cable, but it didn't seem to make a difference. I’m wondering, should I just replace the sensor myself, or does the exhaust leak need addressing first? Could the leak damage the new sensor?

Okay, since wiggling the cable didn't do anything, the sensor itself is likely the culprit. As for the exhaust leak, a big leak upstream might damage the new sensor over time due to excessive heat or condensation, but a small leak is probably a symptom of the sensor failure, for example, in the sensor's housing. To be sure, I would definitely have a workshop have a look.

Thanks for the advice! I took it to the workshop, and it turned out to be a faulty NOx sensor cable connection, like I suspected. They fixed the connection, cleared the error, and the total cost was 95€. The check engine light is now off, and the exhaust seems fine. Appreciate your help!