Ford Ka check engine light and exhaust leak

I had similar symptoms on my Ka. Have you checked the oxygen sensors? A bad one can cause a lot of problems.

I suspected that. Was it just the oxygen sensor, or was anything else involved? Like NOx sensors, particulate filter or the catalytic converter?

Replacing the oxygen sensor fixed it for me. But with the exhaust leak, you should probably have a workshop check the catalytic converter.

Thanks for the advice! I took it to a workshop, and it was a defective lambda sensor like I thought. The total repair was 375€. Your help was great!