CT200h ECU Failure

I've seen similar issues. The ECU in the CT200h is pretty sensitive. Have you checked the wiring harness for corrosion or damage? Sometimes a bad connection can mimic a faulty ECU. What specific error code are you seeing?

I scrutinized the wiring harness and found nothing obvious. The error code is P0606, indicating a processor failure within the ECU. Could a defective main relay trigger such a code?

P0606 definitely points to an internal ECU fault. A faulty main relay could theoretically cause voltage fluctuations that upset the ECU, but it's more likely the ECU itself is the problem. Given the code and your symptoms, I'd recommend taking it to a workshop equipped to diagnose and potentially repair or replace the ECU. Messing with it without the right tools and knowledge can cause more harm than good.

Thanks for the confirmation. The garage confirmed the defective ECU, but it was indeed the main relay. Replacement and reprogramming cost 120€. Worth it.