DS4 NOx catalyst aging and exhaust leak

Sounds familiar! I had a similar issue with my old Opel Astra. The check engine light was on due to a fault in the emissions system. Though in my case, it turned out to be a faulty sensor. Did you check for any obvious cracks or holes in the exhaust?

Thanks for the tip! Where on the exhaust system did you find the cracks on your Opel? And what exactly was the error code that you received?

I didn't spot the crack myself, a mechanic did. But it was close to the catalytic converter, if I remember correctly. Regarding the error code, I cannot recall what exactly it was, but it was related to the catalytic converter efficiency. Best bet is to bring it to a shop to have a mechanic check it out.

Just wanted to let you know, you were right. I took the DS4 to the workshop, and it turned out to be a leak in the exhaust system, which was causing the NOx catalyst to not function correctly. Repair cost was 265€ Thanks for your advice!