Corsa NOx Catalyst Exhaust Leak

Sounds familiar! I had a similar issue with my old Renault Megane. Same engine light, same error code. Did you check the exhaust system for leaks? That's where my problem started.

I've been looking, but haven't found anything obvious yet. Where was the leak on your Megane? Maybe that'll give me a place to start looking.

It was a small crack near the catalytic converter, where it connects to the exhaust pipe. Barely visible, but enough to cause problems. I'd put it on a lift for a good look or take it to a workshop. Saved me a lot of trouble.

I took your advice and found a tiny hole in the exhaust, just before the cat. That was it! A new exhaust section cost me 265€, and the light's gone. Thanks for the help!