Skoda Karoq NOx Catalyst Issue

Interesting issue! I had something similar with my Karoq – also a petrol engine. The check engine light kept coming on, and the error code pointed to the NOx catalyst. Have you checked your exhaust system for any leaks? Even a small one can throw off the readings and trigger that error. I remember that a leak can allow unburnt fuel/air mixture to reach the catalyst, interfering with its function. Is the exhaust louder than usual, or do you smell any exhaust fumes inside the cabin?

Thanks for the quick response! You mentioned a leak in the exhaust system. Where exactly was the leak located in your case? Was it near the NOx catalyst itself, or somewhere else along the exhaust line? And how did you find the leak, just by visual inspection or did you use some kind of diagnostic tool?

Yes, it was incredibly similar! For me, the leak was right where the exhaust pipe connects to the NOx catalyst. A visual inspection didn't reveal much initially, but the workshop used a smoke test to pinpoint the exact location. I understand your concern about the cost; a new NOx catalyst can be very expensive. Given your symptoms (check engine light, error code, exhaust leak), it's highly probable that the leak is the primary cause of the issue. My advice would be to get the exhaust system professionally inspected and repaired before considering a NOx catalyst replacement. I would strongly recommend taking it to a workshop.

Took the Karoq to the workshop and they confirmed a small exhaust leak near the NOx catalyst. They welded it, and the check engine light is gone! Total cost was 265€, which I'm happy with considering the alternative. Thanks again for your help, it really pointed me in the right direction!