Peugeot 308 NOx Catalyst Error and Exhaust Fumes

Sounds familiar. I've got a 308 too, and those were exactly my symptoms when I had a leak in the exhaust system. The ECU detects the NOx catalyst not working efficiently because of the leak and throws the error. Have you checked for any obvious holes or cracks in the exhaust?

Thanks for the quick reply! I haven't had a chance to get under the car properly yet, but I did a quick visual check and didn't spot anything obvious. Where was the leak in your exhaust system?

Mine was a small crack near one of the joints in the exhaust. Honestly, it was hard to spot without a proper inspection. If you're smelling exhaust, I'd suggest getting it checked out by a workshop. It's probably a similar issue and not worth the hassle of trying to fix it yourself, especially with emissions stuff.

Appreciate the advice! I'll book it in with a garage. It was indeed a small leak in the exhaust system, like you said. Cost me 265€ to get it sorted. Thanks again!