I want to know if the Master Cylinder is a week link in 2001 S4's.
The brake pedal suddenly went all the way to the floor (at slow speed 15mph and less) while braking on muddy roads followed by the red brake warning light in the speedometer and no brakes. Not certain if a brake hose let loose or Master Cylinder failure. I am having my 2001 S4 towed to my mechanic's shop for evaluation. Any help would be appreciated.

 

sounds like a leak from a brake line. have you done a brake job recently? if you didnt have a leak i would say the booster is the culprit. check your lines. this is a real cheap fix you can do yourself and even upgrade to stainless steel lines.