I took my S4 in for a noise in the front end that occurs when I brake at a slow speed, usually rolling in first gear. It comes from the front end and sounds as if someone is under my hood with a wine glass rubbing their finger around the rim of the glass, only it is loud. Of course when I get to the dealer I drive the service guy all around the parking lot and it will not make the noise. So without hearing the noise, again it only happens at slow speeds, he proceeds to tell me that it is probably the ABS pump. He said that it builds up pressure and when it lets it out it makes this sound. For some reason that does not seem right to me because I have had cars with ABS before and never had this problem. I left the car there because it also had the check engine light on so maybe they will figure it out. I do not want to be a pain but I just bought the car as a CPO from the same dealer two weeks ago and I hate to hear noises already.