I installed a genuine Audi/VW battery in my 2012 A3 and it came with a sealing plug. The instructions that came with the battery say to put the plug in the same side of the battery as the one you just removed. I put the plug in the side of the battery closest to the positive terminal. However, there seems to be a similar hole near the negative terminal. How do you decide which hole to put the plug in if you did not notice the plug on the old battery and the old battery is gone?
Incidentally, I bought the battery at the Audi dealership in Burlingame, CA and paid $136 plus tax.