Terra turn signal error

That sounds familiar. I had a similar problem with my old Opel Corsa. You wouldn't think such a small thing could cause so much trouble. Did you check the flasher relay?

A flasher relay? I haven't checked that yet. Where is that located, and how would I test it? Is it easy to replace or should I leave it to a professional?

Well, in my case it wasn't the relay, but yeah, that was my first thought too. Turned out to be a corroded connector. But honestly, with those error messages you're getting, might be best to just take it to a workshop. Save yourself the headache.

Thanks, I appreciate the advice! I took it to the workshop, and you were right, it was a defective connector. Repair cost was 95€. Problem solved!