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C6 NOx Catalyst Exhaust Leak

My 2016 Citroen C6, gasoline engine, at 129702 km, has a check engine light with a NOx storage catalyst aging error. I think I smell exhaust fumes more than usual. Could an exhaust system leak be the cause? Has anyone experienced this?

A 2016 Citroen C6 owner reported a check engine light with a NOx storage catalyst aging error and an unusual exhaust smell, suspecting an exhaust system leak. A similar experience suggested that exhaust leaks, particularly around the exhaust manifold or flex pipe, could cause these symptoms and affect fuel efficiency. The recommended solution was to have a workshop perform a smoke test to identify and repair the leak, which was confirmed to be a crack in the exhaust system.

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4 comment(s)

I had a similar issue with my C6. That NOx catalyst is a pain. Exhaust smell and the check engine light are classic signs. Check for leaks around the exhaust manifold and down the system. A small crack can mess with the emissions system and throw off the NOx readings. Is your fuel efficiency worse than before?

Thanks for the tip! Fuel efficiency does seem a bit off, now that you mention it. Where should I be looking for these leaks? Any specific areas that are more prone to cracking or failing on the C6?

Okay, the worse fuel efficiency confirms it. On mine, the flex pipe right after the catalytic converter was the culprit. It had a hairline crack that was tough to spot at first. Honestly, save yourself the headache and take it to a decent workshop. They'll smoke test the exhaust and pinpoint the leak quickly. It could save you from replacing parts you don't need.

Thanks so much for the advice! I took it to the workshop, and you were spot on – it was a crack in the exhaust. It cost me 265€ to get it fixed. I really appreciate the help!

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CITROEN

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