Peugeot 508 NOx Catalyst Aging

I had a similar issue with my 508. The error memory also had this NOx storage catalyst aging message. Did you check for any visible leaks in the exhaust system? That was the culprit in my case.

Thanks for the quick reply! I haven't thoroughly checked for leaks yet. Where exactly should I be looking? Are there any specific spots on the exhaust system that are more prone to leaking?

In my case, the leak was near one of the joints in the exhaust pipe, close to the catalytic converter. Given your symptoms, especially the exhaust smell, I strongly recommend having a workshop take a look. They can perform a proper smoke test to pinpoint the source.

Thanks for the advice! I took it to a local mechanic, and you were right – it was a small leak in the exhaust system. They repaired it for 265€, and the error code is now gone. Really appreciate the help!