Avalon Hybrid Tail Light Issue

Sounds like a potential electrical issue. Have you checked the cable and plug connections to the light switch itself? A defective connection there could definitely cause intermittent problems and trigger a stored error. Does the dimmer switch affect the dashboard lights correctly, or is that acting strangely too?

I haven't checked the connections yet, but that's a good point. Where exactly is the light switch connection located? Is it easy to get to? Also, the dashboard lights seem to be working fine with the dimmer switch, so far at least.

The light switch connection is usually behind the dashboard, near the steering wheel column. While it might be accessible, fiddling with it without proper tools and knowledge could cause further issues. Given it's an electrical problem and you have a stored error, it would be best to get it checked by a workshop. Faulty tail lights can be a safety hazard. Just prepare for about 95€ repair cost.

Thanks for the advice! I was hoping it would be something simple, but I guess it's best to be safe. I'll book an appointment with a mechanic to check the cable and plug connection of the component. Hopefully, it's just a loose wire and nothing too expensive.