marymoeller8

B Klasse rain light sensor issues

I'm having trouble with my 2021 Mercedes B Klasse hybrid. It has 128234 km on it. The rain-light sensor seems to have gone haywire. I'm getting an error stored in the memory. No automatic wiping in the rain, which is annoying. Also, no automatic headlight control, speedometer dimming isn't working, and the lights are just switching on whenever. Could this be an electrical fault? I read about bubbles forming under the gel pad of the windshield messing with the rain detection and car electronics. Has anyone else run into this sensor fault? Is sensor calibration needed?

4 comment(s)

That sounds familiar! I've got a B Klasse as well, and I had similar issues. No auto wipers, lights acting up, the whole deal. Could it be the same thing? Did you check the windshield for those bubbles under the sensor? I wonder if that's a common problem.

I did check for the bubbles, and they're there! So, you're saying you had the same symptoms? What did you do to fix it? Was it hard to get done? Did you need to get the whole sensor replaced?

Yep, same symptoms! Those bubbles were the problem. I ended up taking it to the workshop. They confirmed it was the gel pad issue. I wouldn't try to fix it myself unless you really know your car electronics. Just a heads up!

Thanks for confirming! Sounds like I'm heading to the workshop then. I appreciate the help! I just got it back from the shop. Turns out it was the rain-light sensor. The gel pad had bubbled up, causing problems. They replaced the sensor for 62€. Everything is working now!

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