V50 Exhaust Treatment Malfunction

Rough running and a strong smell point to combustion issues. That leak could be anywhere in the exhaust pipe. Could be pre-cat, post-cat or even the cat itself gone bad. Have you checked for any obvious damage to the exhaust pipe or catalytic converter?

Thanks for the quick response. I visually inspected the exhaust pipe and catalytic converter but didn't find any obvious cracks or holes. What are the chances it could be something like NOx sensors or the particulate filter causing these symptoms?

NOx sensors usually trigger specific codes, and your description sounds more like a primary combustion/lambda issue than a NOx problem. Particulate filters are more common in diesels. Given the age and symptoms, a faulty lambda sensor is still a prime suspect. But honestly, without proper diagnostics, you're shooting in the dark.

Appreciate the confirmation. I took it to a workshop for diagnostics. You were right, defective lambda sensor. Repair cost 375€. Thanks for the help!