Crossland X exhaust treatment malfunction

I had a similar problem with my Crossland X. Have you checked the lambda sensors? A defective oxygen sensor can cause the engine to run poorly and trigger exhaust-related error codes. Is it running particularly rich or lean? You might also want to check the catalytic converter. I hope this helps.

Thanks for the tip! Where are the lambda sensors located? Can I test them before replacing them? I'm getting a strong exhaust smell; could it be related to NOx sensors?

The lambda sensors are usually located before and after the catalytic converter in the exhaust system. You can test them with a multimeter, but unless you know what you're doing, it might be best to take it to a workshop. I had the same strong exhaust smell, and it turned out to be a defective lambda sensor that damaged the catalytic converter. Good luck with the repairs!

Thanks for the advice. I took it to a mechanic, and you were right. It was indeed the lambda sensor, which had damaged the catalytic converter. The repair cost me 375€, but at least it's running smoothly now.