Auto windscreen wipers activate without rain/water

[Norton_San]

Hi all,

My GTi has a pretty annoying habit of activating the windscreen wipers (when set to auto) when there is no rain or water of any kind hitting the windscreen or going anywhere near the sensor. It's been happening for long enough for me to realise there is no dust or bits or anything else hitting the window either which it might mistake for water. They just go on their own over a dry windscreen.

Sometimes it does one swipe, sometimes 10, but always with a slight delay in between. They never come on like as if it thinks its pouring with rain.

Now I'm going to guess the general opinion here will be a faulty sensor but has anyone else had this issue and if so, how was it fixed? Can a service centre reduce the sensitivity of the sensor maybe?

Thanks heaps.

[Harrydhillon]

You should be able to reduce the sensitivity. Either on the wiper stalk or via MFD.

[AdamD]

The sensitivity is adjusted by the toggle switch (with about 4 or 5 positions) on the top of the wiper stalk. Far left is least sensitive.

[Norton_San]

The sensitivity is adjusted by the toggle switch (with about 4 or 5 positions) on the top of the wiper stalk. Far left is least sensitive.

Ah, haha. I didn't know that's what the switch was for. *Face palm*.

I think I just need to go down one level in sensitivity.

Thanks for the reply.

[AdamD]

I think I just need to go down one level in sensitivity.

With my GTI, I used the least sensitive or second least sensitive position when the weather was inclement. The rest of the time I left the wipers in the Off position, because from time to time they're still liable to do the odd 'ghost wipe' for no good reason, leaving streaks all over the windscreen.

Have a play around with the sensitivity toggle next time it's raining. You'll get a good feel for how it behaves that way.

[piper26]

Be aware also that general dirt and road grime will influence the sensor also. So a dirty screen can trigger the wipe Also the sensor only sees a small % of the screen. If the right amount of water has hit the screen at the sensor it will trigger also.

The sensitivity on the stalk is a good place to start.

These sensors are fairly reliable. Only really see dramas when windscreens have been done and the old sensor is transferred over

[wai]

The sensor works sending out infra-red light and then looking for a reflected light back from something like a droplet of water. So anything that will cause the light to reflect back will cause it to trigger. The reflective surface of a grain of sand can trigger it, so make sure that there is nothing on the area of the sensor that might reflect (like a splattered bug). You can adjust the sensitivity, however I've found that if you reduce the sensitivity on which it triggers, it requires a fair amount of rain on the windscreen. I have the stalk in the off position as it is just as easy to turn it on when needed, and I use the auto feature to vary the frequency in light rain because even one step in from maximum sensitivity can see the windscreen with a lot of rain before it starts wiping. Also this allows a flick wipe by pressing down on the stalk and releasing it.

The worst thing that happened to me was when a flock of grass parrots flew across the screen and splattered it with "used seeds" while I was driving at 100 km/h. The auto wipers triggered and smeared it all across the screen!

[Norton_San]

You can adjust the sensitivity, however I've found that if you reduce the sensitivity on which it triggers, it requires a fair amount of rain on the windscreen.

Thanks mate. Yeah I agree about the sensitivity when it comes to rain; at the highest sensitivity it seems to be very good at determining the correct time to start wiping and the wiper speed. So by decreasing it one level it may just end up that it takes to much rain to activate and then I can't see where I'm going.

I never think my screen is dirty when the wipers start doing their own thing but you never know. Occasionally when it does it I will use the washer fluid to try and clear anything off, but sometimes that seems to make it worse as even after it has cleared the water from the washer, it will keep wiping with about 2 second intervals in between so it obviously sees something on the sensor. This annoyed me so much the other day I just turned em off haha.

This is clearly a first world problem I am having; I could just turn the automatic wipers off but then I feel you have a feature in a car that you can't use because it doesn't work properly. Seems like a waste