Aveo Lighting Issues

The symptoms you describe, along with the stored error code, do point towards a potential issue with the light switch circuit. Has any work been done recently on the vehicle's electrical system? It's important to rule out any recent modifications or repairs that may have inadvertently affected the wiring.

No, I haven't done any electrical work lately, other than replacing a blown tail light bulb a few weeks ago. Could a bad bulb cause this kind of problem, or is that a red herring? And if it is the light switch, is it something I can replace myself, or is it more complicated than that?

While a faulty tail light bulb is unlikely to cause the symptoms you are experiencing, it's always best to ensure all bulbs are functioning correctly. Given the error code and your description, a defective cable or plug connection on the component sounds like a very probable cause. If you want to perform the replacement yourself, please disconnect your car battery before any repairs of electric components. If you are not experienced in this area, a visit to a workshop is advisable.

I took it to my local workshop, and it turns out it was a loose connector on the light switch, just like you suspected. They cleaned it up and secured it, and everything's working fine now. The total cost was about 95€. I wouldn't have known where to start without your input!