Wipers not working or staying on even with key absent

I have a 2014 galaxy with auto wipers.

The wipers were either not working at all in the wet and/or working constantly in the dry and wouldn't turn off even with the key out. I had to pull the 30amp fuse under the bonnet to stop them. Put the fuse back in and they stayed off.

They would come on with the lever in the off position whether wet or dry.

I was bemused and had a car I couldn't use in the wet and was no good in showery weather either!

Tried the usual fuse checks and circuit checks then I remembered the windscreen was changed under warranty due to heated screen failure on the drivers side. The screen has a rain sensor built in for the auto wipers. I found a website that suggested unplugging the rain sensor.

I removed the plastic surround behind the rear view mirror and as soon as I unplugged the screen mounted sensor the wipers were restored to normal function, just no smart auto wiping. The auto setting on the lever is now normal intermittent wipe with speed control on the lever.

The cost of a new sensor is 153 GBP, but second hand ones are around 30 GBP on eBay.

Not sure I'll bother to change it as it may still have, or may develop the same fault again. One website suggested it could be caused by dirt in front of the sensor, or also new wiper blades that are not the correct length to wipe over the sensor.

Hope this helps if you have the same problem, and saves the hundreds of GBP in diagnosis by a dealer or specialist.