I've had a 2004 model for about a year now and recently I;ve had trouble where my battery kept dying.. after a few days I realized the problem has nothing to do with the battery or alternator, but there seems to be an issue where the fan under the hood will turn at full power and drain the battery. I'm not sure exactly how long after I turn off the car that this happens but I'd say probably about after atleast an hour or so..

Only thing that seems to turn the fan off is to turn the car back on. At first I thought it was a problem with the thermostat, but I tried turning the car without starting the engine and seeing the guage read and it stayed on the cold side. I figure if the thermostat was giving a false reading then I should see the guage goes up, but then again the fan does shut off when I turn the car on so I don't know..

Is there anyone to confirm that its a problem with the thermostat before I replace it? or any other ideas as to what the problem could be? thanks

 

do u have a mil light on. I would take it to autozone or somewhere and have them scan the car first. It could either be water in your ecu or a temp sensor. But best to have the car scanned before you start to replace parts.

 

I can't confirm for you either way, but my fans suddenly run constantly while I am driving and I am having thermostat stuck open problems. I recently replace my coolant flange and now the thermostat...

Get it scanned and that will point you in the right direction. I currently have a P0440, cooling system efficiency problem.

Good luck and be sure to keep us posted to your findings.

 

So I noticed the anti-freeze link was just slightly below the min level marker, sure enough I topped off and so far the its been left parked with the battery hooked up and no problems yet for about a day now. now sure how exactly this caused the fan to run at full power to the point where it drained the battery but oh well, now i have to find out where the leak is i guess.

on a side note I actually got a $50 ticket for motor running attended because the fan started up while parked once and the meter-maid must have thought the engine was running lol

 

Advise my Audi A4 2005 model, fan starts at full power when parked and engine off, the only thing that stops it is to put in the key and turn on.

 

Advise my Audi A4 2005 model, fan starts at full power when parked and engine off, the only thing that stops it is to put in the key and turn on.

 

From my experience almost all b6 a4 go through this most likely it is the fan control unit it get moister inside or something or check that water has not goten in to where your ECU is bad drain and seal audi messed up on that aspect