Rain Light Sensor Faulty? Auto lights don't work / auto wipers worthless!

[IKE20VA4]

So I have auto headlights & wipers in my A4. If I leave the switch in auto mode now, I get a loud beep when I start the car and the "dipped headlights" signal comes up on my color DIS. The headlights will turn on but the interior dash lights will not. I scanned the codes via VCDS (vagcom) and got the below code in in the Central Electric Module. I thought to myself hmm why did this happen? I did have my car at a body shop about a year ago to the day and I know for a fact they had removed my rear view mirror and dropped the headliner to push dents out of the roof. I remember going to check on my car and seeing the mirror just freely hanging/dangling. I'd been reading and searching all afternoon today and they say when replacing the sensor and (new) gel foil that you want no bubbles and has to be super clean and you should see a deep black color when you are done. So I went out with a flashlight to look and it looks like there must not be a very airtight seal since there appears to be condensation and fogging up of the area where the sensor is. See pic below. ANYONE possibly have this happen? I imagine that maybe when the re-installed the mirror that they didn't apply a new gel foil. Anyhow, wipers are bugging out (basically worthless!) and have to manually turn headlights on (I know, real difficult). I'm debating whether to order a new sensor at $200 and gel foil at $35 or just try a new gel foil to see if I can get a better seal first.

This is where you let me know your brilliant thoughts and opinions. Thanks in advance.

October:
01520 - Rain and Light Recognition Sensor (G397)
37-10 - Faulty - Intermittent

December:
01520 - Rain and Light Recognition Sensor (G397)
37-00 - Faulty

[IKE20VA4]

Part numbers for reference. Most current revisions as of this post.

Rain Light Sensor: 8K0955559D
Gel Foil: 4E0955609

[mtroxel]

I can't tell from that picture if there is a cloud in there or if that white stuff is just on the glass. But, unless your body shop changed the windshield, there would be no reason for them to remove the sensor from the windshield. It would make sense that they might remove the mirror, and let it hang by it's plug (not smart, but I could see them doing it). But if that's what they did, the rain sensor was still stuck to the glass and you don't need a new gel pad. But, they might have messed up the wires there or even left the sensor unplugged. I'd pull the mirror and see if the plug to the sensor is happy.

Here's a pic of my healthy rain sensor.

[IKE20VA4]

I can't tell from that picture if there is a cloud in there or if that white stuff is just on the glass. But, unless your body shop changed the windshield, there would be no reason for them to remove the sensor from the windshield. It would make sense that they might remove the mirror, and let it hang by it's plug (not smart, but I could see them doing it). But if that's what they did, the rain sensor was still stuck to the glass and you don't need a new gel pad. But, they might have messed up the wires there or even left the sensor unplugged. I'd pull the mirror and see if the plug to the sensor is happy.

Thanks for the tip. It is cloudy under the glass. I agree with there being no reason to it affecting it unless they did just let the mirror hang and not unplug it. They maybe I just need a new gel pad. I will check it out tonight.

[mtroxel]

Yea I'm sure a cloud in there is going to really fool that sensor. Some one here got a new pad and did that job himself. Search a bit...it was in the last year he mentioned it.

[Charles.waite]

My rain sensor is a bit iffy. Sometimes it works just fine but often it has terrible rain sensing abilities right after starting the car (YOU HAD ONE JOB!!!)

My thought is a bit of moisture he somehow made its way into the sensor and fouled up the pad so when it's cold it's a bit fogged and once the cabin gets up to temp and its defogger it works as intended. Could be wrong but I was thinking of just replacing the gel pad and cleaning the windshield surface really well, maybe win isopropyl alcohol or something, before putting the new gel on.

Symptoms are mainly that the wipers wait too long to sense rain or wipe too slowly so I have to manually kick them on or toggle the sensitivity dial to get them to cycle once.

[IKE20VA4]

Decided to order the gel pad foil thingy and give that a whirl since I found a Porsche one on ebay for under $20. It gets here Monday the 14th. So stay tuned.

http://www.ebay.com/itm/201382491002

[IKE20VA4]

The new gel pad seems to have done the trick! At least for the light sensing portion. Somehow it stopped raining at the moment so I have not been able to test out the wipers yet.

Old sensor cleaned up best I could with 91% isopropyl alcohol. At first I was using my fingernail to scrape off the old gel/glue and you can see I scratched it up a bit. For the rest I switched to a microfiber towel with alcohol on it.



Old sensor installed with new gel pad from outside. Cloudy/hazy under glass is gone!

[mtroxel]

Nice job! Hope the rain parts works.

[Charles.waite]

Bumping this because I just ordered one of these gel pads since my wipers being being ridiculous on my commute home in the rain. Will report back when they arrive to see how they work after.

[mtroxel]

^^^Please do. I'd like to know if they do anything too.^^^

[Charles.waite]

Installed the gel sensor tonight. It started raining mid-install so I had to rush a bit, but a quick test with a bit of rain showed the rain sensor still worked so I didn't totally blow it. Its supposed to rain tomorrow so I can provide a better feedback on how this worked out tomorrow. The install was a bit fiddly, the gel pad is a bit awkward to deal with because it simultaneously sticky and slippery. But fingers crossed it helps resolve my issues. I took a lot of time to clean off the sensor. There seemed to be a lot of fairly persistent residue on the sensor face itself, but I just used some natural glass cleaner. If the results tomorrow don't pan out I'm going to pickup some isopropyl alcohol and redo the install...

[Rol-co]

Installed the gel sensor tonight. It started raining mid-install so I had to rush a bit, but a quick test with a bit of rain showed the rain sensor still worked so I didn't totally blow it. Its supposed to rain tomorrow so I can provide a better feedback on how this worked out tomorrow. The install was a bit fiddly, the gel pad is a bit awkward to deal with because it simultaneously sticky and slippery. But fingers crossed it helps resolve my issues. I took a lot of time to clean off the sensor. There seemed to be a lot of fairly persistent residue on the sensor face itself, but I just used some natural glass cleaner. If the results tomorrow don't pan out I'm going to pickup some isopropyl alcohol and redo the install...

And how did this end? Solved the problem?