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R Klasse rain light sensor issue

My 2011 Mercedes R Klasse with a gasoline engine, which has 209317 km, has a malfunctioning rain-light sensor. There's an error stored, the automatic wiping doesn't work in the rain, and the automatic headlight control and speedometer dimming are also not working. The lights sometimes switch on randomly. Any ideas?

4 comment(s)

That's interesting. I had very similar symptoms on my R Klasse. Does your windshield have any bubbles forming under the gel pad where the sensor sits? That was the root of my electrical fault, especially the rain detection issue.

Bubbles under the gel pad? I'll need to check. Where should I look?

Yes, bubbles. It's apparently a common issue. The sensor is behind the rearview mirror, on the windshield. If there are any bubbles between the sensor and the glass, that's likely the problem. I suggest visiting a workshop for sensor calibration or replacement.

Thanks for the tip! You were right, there were bubbles. I went to the workshop. The sensor was faulty because of it, and it cost me 62€. Now everything is back to normal.

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