Coolant Leak?
 

I have a 2006 A4 2.0T with approx 16k miles on it. I recently noticed that the coolant reserve tank was approaching the minimum level, and also noticed a light pink crust around the tube attached to the tank (see attached picture). The dealership in my area is subpar to say the least, so before taking it to be looked at, wanted to see if anyone on here had encountered a similar problem. Also, if I just want to top off the coolant tank, do I have to use Audi factory coolant, or would something I pick up at an auto supply store suffice?

I had something similar happen to my 05 a4. The coolant tank was leaking and I took it to the dealership to get it fixed. Had I known what the problem was then I would have done it myself. Apparently, "the upper coolant pipe bleeder nipple was leaking" according to the service report. I would guess that the pink crust you see is dried up coolant since the audi coolant is pink. Before I took it to the dealer, I added some regular coolant I bought at an auto parts store and it worked fine in the meantime. I am not sure if you can buy the parts yourself but, I am pretty sure that the problem I had is the same problem you have. Since your car has 16k miles, i would take it to the dealership to get it fixed anyway since it is covered under warranty. I hope this helps.

did u check your coolant immediatly after turning your car off....because then it would read as if your coolant is low when really it just hasn't left the engine yet

but since u have the crust it def sounds like a leak....check your hoses they can go bad on occasion and make sure all fittings are on there tightly

yeah, that pink crusty stuff is most definitely coolant that has escaped thru a leak. i would take it straight to the dealership as it should be covered under warrenty and they will most likely replace the bleeder nipple that greg was talking about