No Brake nor Power!

sounds like the servo had lost all vacuum to me!

did it just happen the once or is it like it all the time!

Check all brake servo pipes i think its just a simple leak.

Check the metal nipple going into the vacuum pump on the rear of the engine.

bleachy said:

Check all brake servo pipes i think its just a simple leak.

Click to expand...

Sounds like the servos crackered, common problem on a4s and you lose boost too, think it was something to do with water getting into servo around bulk head, see if there's water around battery area,if so you need to sort the drain hole and probably replace your servo.

if water has gone in the servo you would see it when you take the battery cover off there would have to bee a lot in the chamber and then thats dont to audi as far as i no i had this with mine and it was the pipe that goes into the vacuum pump cost just time to fix

I've just done the servo on my sons A4 due to it getting damaged by water... the area under the screen around the battery and servo fills with water if the drain holes get clogged... the servo then sucks water in and this water stops the large piston inside the servo from moving.... we drained the water on my sons and eventually the water drained out of his servo too but in time it caused corrosion inside the servo and the rust jammed it all up again so it needed a new servo... the water wont get into your brake fluid as it's seperate from that ..... you say you have lost boost too so i'm more inclined to think that you have a broken or leaking pipe.... check the thick black plastic pipe that goes into the servo, it goes through the bulkhead and the connects to the rear of your engine at the top... you'll have to take a few covers off to get access to it all