Terrano NOx Catalyst Aging and Exhaust Leak

I had a similar issue with my 2014 Opel Insignia. The check engine light came on and error codes pointed to catalyst inefficiency. Did you notice any changes in fuel consumption or engine performance alongside the exhaust leak? A faulty exhaust manifold gasket caused similar symptoms for me.

Thanks for sharing. I haven't noticed any changes in fuel consumption or engine performance. How did you pinpoint the faulty exhaust manifold gasket on your Opel Insignia?

I suspected a leak because of a hissing sound, especially during cold starts. A smoke test at a workshop confirmed the leak was at the exhaust manifold gasket. Given your Terrano's age, a similar issue is possible. I'd recommend a thorough exhaust system inspection at a qualified workshop.

I followed your advice and took it to a workshop. They confirmed and repaired a leak in the exhaust system. The total cost was 265€. The error codes are cleared, and the check engine light is off. Thanks for your help.