Skoda Superb rain light sensor issue

That certainly sounds like a malfunctioning sensor could be the culprit, impacting multiple car components tied to that auto sensor. Does your Skoda Superb, even with just 40468 km, display any error codes related to rain detection or an electrical fault in the error memory? If so, recording those codes might provide a clue. Before concluding it's the sensor itself, have you checked the wiring harness and connections to the rain-light sensor? Water ingress there could mimic the symptoms you're seeing.

Yes, there's an error stored in the error memory related to the rain-light sensor. I've also noticed that there's no automatic wiping mode in the rain and no automatic headlight control. Plus, the speedometer dimming doesn't seem to work, and sometimes the lights switch on seemingly randomly. Is there a specific area of the wiring harness I should focus on?

Given the additional symptoms and error code, it does reinforce the likelihood of an issue with the rain-light sensor itself, or its immediate environment. While I can't definitively say without inspecting it, I've heard of bubbles forming under the gel pad of the windshield, which can interfere with the sensor's readings and cause such seemingly random faults. Consider investigating that. Ultimately, a visit to a workshop is warranted to properly diagnose and rectify the issue.

It was exactly as you described, bubbles under the sensor's gel pad. A new gel pad application and recalibration cost me 62€ and resolved all problems. Thanks for your help!