Sci-fi_Wasabi

If you are having rain sensor issues, the gel pack is a good place to start.
Mine acted weird so I took a look. Apparently the 1st owner had the windshield replaced at some point and the fitter did not even bother to put a gel pack in!
(WARNING: DO NOT REMOVE THE SENSOR AND START THE IGNITION... SOMETHING BAD HAPPENS WITH CALIBRATION... ( I don't know what, but i don't want to find out)
Here is what you need:
1. really good Windex or Isoprpyl alcohol, a lens cleaning cloth, small screwdriver, the gel pack.
(I dont know how to insert pics in my paragraphs)
2. The gel pack is small, and expensive. Interestingly Porsche and Audi use the same part & part number... but Porsche sells it for 1/2 as much, so I purchased a Porsche one.
3. The rain sensor (from the outside is where the upside down tear drop area is by the rear view mirror mount, check that there are no bubble there and there is a nice deep black contact area.
4. (pic2) Remove cover in back of rear view mirror, it just yanks off easily.
5. Next you see a silver snap in ring pressing the sensor in place, pry it out by the tabs on edge with a small screw driver. Pic 3 is how it looks with the tab removed (round part is sensor
6. Ok, so now remove the sensor, dont touch or scratch the front.... naturally mine had a big fingerprint on the front and some scratches courtesy of whoever replaced the windscreen last. DONT TURN THE IGNITION ON. (Pic4)
7. Ok, this is best done with the gel pack and surfaces warm, like 70 degrees, so work when its warm or bust out a blow dryer to slightly warm materials.

This is the most unforgiving part of the whole thing... time is of the essence, because there is invisible lint and dust flying all over the place (you can see it in the sunlight) so the longer a surface sits the more accumulates. Wipe the lens and area on the windshield with windex, let it dry, then use a lens cloth.
8. Take the paper backing off of the gel and apply it to the sensor starting from one side to the other so no bubbles form (it really does not matter since it all came apart for me during install) (pic 5...i have it in the sun warming up... wait a minute... there is a max of 5 pics... so I'll stop here with the pics.
9. Press the sensor in, starting lower to top or top to lower, just not flat in, so bubbles can move out. (you will see a nice deep black color form where the is good contact at all surfaces
10. It turned out ok, i just had a small bubble at the bottom... my quest for bubble free-ness caused a great mess. As i pressed harder on one side, the gel separated from the sensor, got more bubbles, pulled it out. now i got some finger prints on the tip of the gel... tried to wash it off with more windex, (douse your finger tips with windex to avoid prints) but it was not quite the same... installed twice again, finally got it so it was pretty good, just could not get rid of a bit of bubble at the tip near the IR emitter.
Worked fine with a spray bottle, will see if it works in the rain.... Just to help others if anyone knows how to calibrate the sensor for those who are replacing it, that would make a nice post under this thread too.

aTOMic

Wow, thanks for this Wasabi. About how much were the parts?
-Tom

mishar

Very good to know. Thanks.

Sci-fi_Wasabi

GelPack $17 at ECStuning + about $8 S&H, Someone sells them on Ebay too, but for a bit more, There are generic ones available from some companies, and even some kind of thing called SensorTak that allows you to make it.

Sci-fi_Wasabi

Got some rain tonight and went for a drive. rain sensor doing its job now, although I wish we had an option for adjusting intermittent slow wiping... I'm just used to it, and I like the uninterrupted rhythm of the wipers.