ECU Fan issues after Heavy Rain? [=(]

[Zoidbort]

Howdy all,

So last week in Vancouver, after the Radiohead show, I drove home in a lovely torrential downpour. No issues there but in the morning when I went to start my car, it was almost dead but it had enough juice to get the air pump fan going and it just kept running, even with my key out of the ignition. So my bro gave me a boost and as soon as it started up, that air pump fan just kept going. We proceeded on our road trip down to Washington/Oregon to do some camping and the entire trip was plagued with this issue.

Every time I stopped my car and got out, within 30 seconds the air pump fan would kick in and not shut off. My battery would die withing 20 mins of the fan running so I had to disconnect it every time I stopped After the 2nd day, my fan stopped and has not run since, so I suspect that it burnt out. Now my rad cooling fan does it!?!? Every time I shut the car off, it kicks in and the only thing that stops it is turning my key in the ignition. Thus I still have to disconnect my battery every night at home. Needless to say our trip was cut short as I started to get a check engine light once we hit Oregon. According to my VAG, that was due to minor misfiring which I remedied by going to the Audi dealer in Oregon and getting a new clip for the wire harness to one of the coil packs (I discovered then that all the wires going to those 4 individual clips have their sheaths cracked due to engine heat - really Audi, after 6 years that is happening? $1200 for a new harness too...come on, but that is another story).

An Audi tech at the dealer told me that when the Audi's are chipped, some companies do not "towel" the ECU and thus in times of heavy rainfall the ECU can get moisture in it and cause the fan relays, which are on the underside, to get moisture in them and cause malfunction such as always staying on etc. Can anyone confirm this and does anyone have any ideas or suggestions for my weird and frustrating issue here? Cheers in advance guys for the help!

[bananas]

I would bet your ECU box cover is either cracked, broken, or not tightened down properly.

[Zoidbort]

Mmm well I will take a peek. Do you think the relays are toast now or just remaining moisture in there is still wreaking havoc? Can I use a blow dryer on low to dry it out or?

[old guy]

Bananas is right on the money. You have a leaking ECU box. the ECU master control relay sits in the bottom of the box when it gets wet it can power up the fan control relay. you can try drying it out and you might get lucky. If not a new relay and ECU box seal and or cover is in order.

Cheers!

[absolutegtr]

Sounds like your Audi tech knows his stuff.

The same thing happened to Winston.

[Zoidbort]

Yuppers, I took the ECU cover off and the whole back of it was cracked along with the back 2 bolt holes broken off as well. The bottom of the ECU was filled with water and 2 of the 3 relays were rusted out inside and filled with water and muck. ECU is still sealed and OK. Dried everything out and sprayed the connectors down with brake cleaner to clean out any corrosion and muck. Everything is OK now besides the 2 relays which need replacing. However on the way home from my folks after doing the work my ECU, my EPC light came on and my car lost all power and stalled on the highway!! I restarted it and it ran 100% but the EPC stayed on. You think this is all related guys? Time for a VAG scan tomorrow.

[Zoidbort]

Man...my 373 and 219 relays are toast. $110 for both from the stealership!!! What a joke! Anyone know a cheaper place to get relays? I suppose I would end up having to wait etc however if I went the ordering online route.

[kwimberly]

Ok - now I know why I need replace the back screw that I purposely left out of the ECU cover to make it easier to take off. That sucks, man! I'll buy a screw from you if I can't find the one I took out!

[Zoidbort]

Well I found one relay that Audi wanted to charge me $58 for here:

http://www.autopartsway.ca/AutoParts...ber=8d0951253a

but the other one (443 951 253 AA) cannot be found.

Wimberly, I too am missing those back screws as my cover no longer has the tabs those screws go through to hold the backside down! I need 2 more screws and a new cover to boot :(

[absolutegtr]

Can you take the relays apart and possible clean them up?

[old guy]

Well I found one relay that Audi wanted to charge me $58 for here:

http://www.autopartsway.ca/AutoParts...ber=8d0951253a

but the other one (443 951 253 AA) cannot be found.

Wimberly, I too am missing those back screws as my cover no longer has the tabs those screws go through to hold the backside down! I need 2 more screws and a new cover to boot :(

Plug the part number into option 2 of this link. Clicky click You will find the relay you need listed for $26.

Here is another source:Clicky click

[Zoidbort]

Cheers for the links, much cheaper! I think I will go the stealership route however as it will allow me to get them 2-3 weeks faster. I am now currently driving my '99 Passat 1.8T, which has to be sold, but I am missing my A4!

This place has one of the two I need for $4.36 CAN!

http://www.autopartsway.ca/AutoParts...=W0133-1641108

[Zoidbort]

So after plopping in the new 443 951 253 AA relay, the car is perfect with no more issues now. Cheers for all you help, I am sure I will be back :P

[goVermont]

The same thing you describe just happened to my 2002 A4. Dead battery in the morning. Luckily, after a few days of jump starts, I caught the fan on once. My mechanic replaced the temp sensor/switch. Didn't help. He said he checked for water in the ECU case having read about the problem. However, when I took the case apart, I found a bit of water in the bottom. The 219 fan relay was corroded, and when I pried the case off, there was muck inside. I cleaned this off, sprayed WD 40 everywhere, and reinstalled it. The contact points look OK We'll see. I'll probably replace it anyway. . I did notice the ecu case cover was broken in the back under the bonnet where you can't get to the screw. I also took a 1/8 inch drill and bored a little drain hole in the bottom so water can't collect again. What does anyone think of this fix? (I'll let you know if the cleaned relay works--the fan not going on would be worse than not going off.)

[old guy]

My recommendation would be to go ahead and replace the ECU cover. Is it worth taking a chance with a $900+ piece of moisture sensitive electronics?

[PETARDED]

I still have the "running fans" issue with my 04, replaced the sensor twice, that apparently didnt remedy it. Now Im going to check the ECU box to see if this is the issue.

[goVermont]

Old Guy--thanks for your thought. Do you know how to get at that back screw of the ECU cover? Apparently the last guy who tried broke the cover back there.

[old guy]

If you remove the wiper arm you can get to it with a ball end Allen key wrench. It is quite tedious but doable.

Edit: This might help Clicky click

[old guy]

I still have the "running fans" issue with my 04, replaced the sensor twice, that apparently didnt remedy it. Now Im going to check the ECU box to see if this is the issue.

Just to be clear, the "running fans" issue being caused by water in the ECU box is when the fans are running after the car is turned off (due to a shorted relay). If yours are running continuously only when the car is turned on you may have a different issue.

[3.0allwheelaudi]

this happened to me from the previous owner, the ECU box was cracked and water leaked in after a tropical storm. the first relay to go was the fan relay but a few months after the start relay went out, left me at walmart for a few hours lol. i suggest changing all them relays if you havent already lol sorry i didnt want to read all the comments above.

[skeeball]

Here are the part numbers for the ECU cover and the screws that hold it down. In case anyone needs them.

8E1 907 613 D cover
N 907 315 01 screw

[festerfm]

i used to have a similar issue, but like was said, mine was only when the ignition was turned on.. both electric fans would come on full blast, sounded like a jet plane taking off. i changed the green coolant temp sensor on the back of the block and it went away for quite some time. now, maybe once every 2-3 weeks or so, the fans kick on but not for long.. someone said about an issue w/ the fan controller over top of the radiator. should it bother me any bit, i'll check into that next.. too bad there's noone local w/ a known good part

[goVermont]

just to update the report--I did pry open the fan relay, cleaned out the muck and cleaned the contacts. Sprayed with WD 40 and reinstalled. This am the car started just fine, sans jumper cables!, and when driving it, the fan came on at the appropriate time. So, the relay can be "fixed", though this seems like a false economy to me! But it will take me a few days to get a new one.

[32_d3gr33s]

this happened to me from the previous owner, the ECU box was cracked and water leaked in after a tropical storm. the first relay to go was the fan relay but a few months after the start relay went out, left me at walmart for a few hours lol. i suggest changing all them relays if you havent already lol sorry i didnt want to read all the comments above.

I have a 2003 a4 And the only relays i can find are under the dash.. There don't seem to be any in the ECU box... Can you tell me which one is the fan relay?

[bmags88]

Same thing happened to me. My 219 relay was $40 and the ECU cover was $40 at the stealership.

[bradman]

WOW!!!! I have been having the same problem for about the past month and couldn't figure it out. Just went out and cleaned the terminals and it is working all good now. You guys are a life... car savior. Thank You.

[sa3dos]

Hey; I have an issue with my fans not working at all; thus overheat .. having read this thread, it seems like Water contributes to fan malfunction Issue. Given that I rinse my engine bay once every 2 months; my problem could very much be related to this, or not (still worth examining before I go buy new temperature sensors and fan switch; that am not 100% sure if it will fix my overheat issue)

I will post back the findings..

Link to my Overheating Issue thread here

[audidude86]

Man...my 373 and 219 relays are toast. $110 for both from the stealership!!! What a joke! Anyone know a cheaper place to get relays? I suppose I would end up having to wait etc however if I went the ordering online route.

i know when i got my 219 relay it only costed 25 bucks at advanced auto part and i got it the next day

[sa3dos]

Hey; I have an issue with my fans not working at all; thus overheat .. having read this thread, it seems like Water contributes to fan malfunction Issue. Given that I rinse my engine bay once every 2 months; my problem could very much be related to this, or not (still worth examining before I go buy new temperature sensors and fan switch; that am not 100% sure if it will fix my overheat issue)

I will post back the findings..

Link to my Overheating Issue thread here

ECU, relays are all fine. No signs of water leak. My finding confirms the certainty that non-operational engine fans are not linked to ECU/relay water leak or damage. I will pursue the issue by replacing temperature sensors.

[M.Andrews]

I experienced the same issue with my 2002 Audi A4 1.8t with both fans running randomly when the car was not running. Sometimes to the point of killing the battery.
I found that one of the ECU cover screws (the one directly below the driver's side wiper attachment) was not tightened at all and the ECU compartment was exposed.
I opened the ECU cover, lifted up the ECU and found water stains on the lower half of the ECU compartment.
I inspected relays 373 and 219 and found that 219 was rusty and damaged.
I pried open relay 219 and found that the tiny spring holding the relay in the open or off position was rusted and broken at one end and had fallen off.
I used another loop from the spring and re-attached it to both connection points, snapped the relay back together, cleaned all of the relay connection points with WD-40 and a Dremel tool then reattached and reassembled everything. I removed the driver's side wiper so that I could reach the hard to get ECU cover screw.
The intermittent fan issue was resolved (but the rusted relays should be replaced asap).

[johnny quattro]

I have a 2003 a4 And the only relays i can find are under the dash.. There don't seem to be any in the ECU box... Can you tell me which one is the fan relay?

Please help! I've a 2004 a4 quattro 1.8t. Did you ever find out where the 219 relay was located? There are no relays in my ECU box. Thanks in advance!

[heywier427]

holy noobs batman!

[pape]

Please help! I've a 2004 a4 quattro 1.8t. Did you ever find out where the 219 relay was located? There are no relays in my ECU box. Thanks in advance!

Inside the ecu box you will see the ECU, and under the ECU you will se 2 relays, the 219 relay has the numbers "219" stamped on it.

[ilko]

I have a spare 219 relay, if anyone's interested shoot me a PM.

[johnny quattro]

Many thanks for the reply!
I have spent several mornings of battery boosting because the fan was operating and draining the battery after I had put the car to bed at night.
I opened the ECU, lifted both the ECU's and found the relay.
And yes, there was an inch of water in the bottom, with a clear watermark half way up he relay.
Cleaned up the relay (refitted the tiny spring) and reinstalled.
I put 2 x 1/4" holes in the bottom of the ECU box to ensure good drainage in the event of additional water seepage inside.
Talk about a design flaw!
Everything now works great!
Just checked the battery and fan status after 6 hours in the garage. Battery 100%, and the fan hasn't been turning on while standing with the key removed.
Thanks again from a noobie!

[johnny quattro]

Thanks for the offer of a spare, but I just received my replacement through Audi parts and service, $51.
Wish I'd have waited a day longer!

[aaronamerica]

This just happened to me! This thread just saved me from buying unnecessary parts

[mr_esmit]

This thread just saved me a bunch of time at the shop. Thanks guys.

[mr_esmit]

This thread just saved me a bunch of time at the shop. Thanks guys.

My car wont start now. I'm guessing the other relay is fried also, even though the shop cleaned it up and said everything was ok....

Anymore relays we should change out in the ECU??? I'll probably drill the hole in the bottom of the ECU box as other users have done a get a new cover as well.

[ecbo0m]

Anyone know which fuse to pull to stop the fan from running when car is off? Temp fix until I can open the ECU to see if flooded ECU box is the issue.