Seat Toledo NOx Sensor Issue

I once had a similar problem with my Toledo. The check engine light was on, and the error code pointed to something in the exhaust system. Have you checked the catalytic converter? I am not an expert but to me it sounds like a clogged catalytic converter. It is like a blocked artery in a human body, causing all sorts of problems.

Catalytic converter, huh? Interesting analogy! But the error memory specifically mentions the NOx sensor. Could a faulty catalytic converter trigger the NOx sensor?

Yes, a faulty catalytic converter can affect the NOx sensor readings, but if the error points directly to the sensor and you are smelling exhaust, I would first focus on the sensor itself and its connections. Given it is a 2002 car, the sensor may have reached its lifespan. The best course of action would be to visit a workshop.

Huge thanks for the insight! Turns out it was indeed a faulty connection to the NOx sensor. Cleaned it up and the error is gone. Cost me 95€ – much better than replacing the whole emission sensor!