C1 Turn Signal and Speedometer Error

I had similar issues on a 2014 Opel Astra. The error message and lighting fault suggest an electrical problem. Was there any external event, like a minor collision, or did it happen spontaneously? What have you tried besides checking the error memory?

No collision or external event. It arose spontaneously. Besides reading the error memory, I visually inspected the turn signal lamp for a broken lens or loose connections, but found nothing obvious. Was there a particular area in the Astra's electrical system where you saw the fault?

In the Astra, the problem was in the wiring harness to the signal lamp. The mechanic found a corroded connector. It's probably best to have a professional do a thorough inspection. I had to go to a workshop. I'd advise you to do the same.

Thanks for the insights. I'll arrange a workshop inspection of the wiring and connectors. The estimated repair cost is around 95€. Thanks for confirming my suspicion of an electrical fault.