I have a 2012 A6 and when I disconnected my battery and reconnected it, my power steering failed. Took it to the dealership and recorded the battery. Power steering worked for a few days, but the over the course of about 10 minutes one day while driving, my power steering light went yellow and then red. I then lost power steering all together. Any ideas on the culprit and part number? Trying to find a part if nessesary instead of buying it from the dealer.