Peugeot 207 rain light sensor problem

That sounds familiar! I have a 207 myself. I seem to remember a similar problem with the rain sensor and headlights. My wipers were also acting strangely. Did you check if there is anything visually wrong with the sensor on the windshield?

Visually wrong? What should I be looking for? I gave it a quick look, but nothing jumped out. Is there a specific area to focus on? And what did you do to fix it?

I eventually took it to a workshop. They said bubbles had formed under the gel pad of the sensor where it contacts the windshield. This was causing the sensor to malfunction, and it's apparently common. Check for those bubbles first. It might be best to get it checked professionally.

Bubbles under the gel pad, got it. I'll have a closer look, but a workshop visit sounds likely. It was exactly as you said, bubbles under the gel pad! Cost 62€ to sort.