S40 Rain Light Sensor Fault

I have a 2000 Volvo S40 diesel. At 167922 kilometers, the rain-light sensor appears faulty. Symptoms include an error stored, no automatic wiping in rain, and inability to automatically control headlights. The speedometer dimming is not working, and the lights switch on randomly. Could bubbles under the gel pad of the windshield cause this, or are there other things to check?

4 comment(s)

Sensor fault on an S40, eh? Sounds familiar. I had similar issues although I never suspected the gel pad. Does it also impact the automatic headlight control? I had the same, plus that random lights-on issue. Have you had a diagnostic scan done? What codes are showing?

Yes, the automatic headlight control is affected, as are the speedometer dimming and random light activation. A diagnostic scan flags an error related to the rain-light sensor. Do you think the gel pad bubbling could be the cause, or was your problem solved another way?

OK, so the same symptoms as me. The gel pad was the root cause in my case. I’d booked the car in with a local independent garage. They confirmed the pad issue and replaced the sensor after attempting to repair the pad. I really would recommend you take it to a specialist. Will save you time in the long run.

Thanks for the insights. Based on your experience, I will focus on the rain-light sensor and the gel pad. A visit to a workshop seems necessary. The repair cost 62€.

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