2004 A4 3.0, 55,000 miles
I had the water in the ECU housing issue which caused the fan to run while the car was off. The (4) relays within the housing were corroded; I dried them out in a bowl of rice which fixed the fan issue and then later replaced all of them.
Now, the CEL is constantly on and the ESP light is on intermittently albeit most of the time. When I first start the car, the idle is sometimes erratic and it will occasionally drop in RPMs enough to stall. When I first start it in the morning and begin to drive, it will occasionally feel as if there's no power. This goes away and the car will drive fine. When I get to my destination and put it in park ( auto tranny) it will occasionally idle funny and sometimes die.

It's throwing three codes:
P0102 MAF/VAF Circuit Low Input
P0172/0175 System to rich (Banks 1 and 2)

I've checked for vacuum leaks, I've cleaned, then replaced the MAF sensor. No fix. An Audi repair tech acquaintance of mine scanned it and was measuring a voltage drop.

Could the relay sockets or contacts with the relays be faulty due to corrosion? I've sprayed them with electronic contact cleaner but to no avail.

I'm getting pretty frustrated and am considering selling the car but the CEL issue needs to be cleared. And if I fix the problem, I'd probably be very happy with the car. Looking for all the help I can get. Thanks in advance

 

If the ecm got wet there is a good chance it is toast! They do not do well with water. Did you open it? Was there green **** inside? If there is/was stick a fork in it.
As far as the relays i would just replace them they are cheap enough.

BTW ,How did the ECM get wet? Are any other modules wet?

 

I bought the car from a private seller and a month later we had some pretty constant rain and problems started happening. Plenum drain under the battery was plugged and there was a half-inch of water in the housing. I'll open the ECU and check. I can Dremel slots in the security screws to turn with a flathead screwdriver, right?

 

I think they might be tamper proof torx , not sure without looking. They are cheap enough.
It would be best to keep metal filings away from the internals or the connector side of the ECM if it has to come to that.
Also remember it is a lot easier for the water to get inside then it is to get it out.
Will probably find green house inside.