Seat Exeo NOx Catalyst Exhaust Fumes

The Exeo, nice car. I had a similar issue with my emissions system. Check engine light, error codes... the whole shebang. First thing I'd suggest is to thoroughly inspect your exhaust system for any signs of leaks. Even a small one can throw off the readings from the sensors related to the NOx storage catalyst. Is the exhaust louder than usual?

Thanks. How exactly did you find the leak? Did you see it, or did you have to use some special tool?

Well, I couldn't spot it myself. A mechanic used some kind of smoke test to find it. Basically, they pumped smoke into the exhaust and watched where it came out. Turned out to be a small crack in one of the pipes. Given your symptoms, especially the exhaust smell, I'd say it's worth getting it checked professionally. Could save you money in the long run, plus you’ll be contributing to better air quality. Car diagnostics are key in these situations.

Thanks for sharing your experience. I took it to a mechanic and they found a leak in the exhaust system, just like you suspected. Cost me 265€ to fix, but at least my check engine light is off and hopefully, my fuel efficiency will improve. Appreciate the help.