Panda rain sensor malfunction

That sounds suspiciously like a rain-light sensor fault. I had a similar experience with my Opel Astra, although the symptoms weren't exactly the same. The error memory was full, the automatic light control was gone. Does your windshield have the original gel pad for the sensor? Are there any bubbles forming under the gel pad?

Thanks for the quick response. I haven't specifically checked for bubbles, but the windshield is original as far as I know. Where exactly should I be looking for these bubbles? Is it easy to spot, or do I need a magnifying glass?

The bubbles are between the sensor and the windshield, under the gel pad. You should be able to see them if you look closely at the area where the sensor is mounted to the glass. If bubbles are present, the sensor isn't making proper contact and can cause all sorts of electrical gremlins. I would recommend taking it to a workshop to have it properly diagnosed and potentially recalibrated or replaced. In my case, I had to get the sensor replaced.

Alright, thanks for the advice! I checked and indeed there were bubbles under the gel pad. I took it to the workshop as you suggested. They confirmed the sensor was faulty due to the bubbles and replaced it. It cost me 62€, but now everything is working perfectly again!