I have had my C280 for a little over three years now and up until about two months ago the rain sensor worked perfectly. Now when I turn it on to the sensor it doesnt stop. Even if there are only a few drops on the windshield it wipes like there is a down pour. I have tried changing the wiper three times and cleaning the wiper blade and the sensor, nothing seems to help. Occassionally it will 'reset' and work fine for awhile but soon it reverts to its mad wiping. I am at a loss as to why it is doing this and dont know what else to try. Any ideas?

 

I have same problem with 2007 C280. If you resolve that let me know.

 

Just wondering out loud - how about cleaning the glass in front of the sensor with something such as alcohol or acetone? Could something be on the glass?

I noticed on my 210 that if we go for a long spell with out rain, and the only thing the windshield gets is soap and water from washing the car, the rain sensing tends to drive the wipers full time until the scum is wiped from the windows. Maybe you have some tough scum?

 

Ya it does help for first 5 min. of driving then goes crazy again (with new OEM wipers).

 

I have same problem and went to dealer and they could not fix problem. At times with little rain it goes into fast mode and does not stop

 

if your car is under warranty take it to dealer. if you are sure it is the sensor, get a new one and any auto glass shop should be able to swap it out (i just had new windshield put in my 05 c-class, and the glass guy said it is one of the easiest windshields to swap).