I talked to a mechanic who didn't have any ideas for me so hopefully someone here has some insight. It has been cold--in the single digits--for the past week and my brakes start out feeling really hard in the morning and the pads seem to be dragging on the rotors a bit, like the pistons are not retracting properly. If I start to drive a bit (after letting the car warm up for a half hour) the brakes get harder and then the ABS and ESP lights come on and the brakes completely lock on. By flooring the accelerator, I got myself to the side of the road, but it is like driving while pushing down hard on the brake pedal. I turned the car on and off several times but the abs/esp lights, and brakes, stayed on. I came back to my car on the side of the road 45 minutes later and everything worked great; the next morning same thing..I didn't leave the property this time though. I replaced the booster and bled the system in July, everything had been good since then. It is a 2002 S6. Any ideas???

 

So it's always a good idea to take a look at things to see if there is anything obvious. Didn't do this right away because it was cold and I didn't have a garage. It might be a problem that my mc and booster are encased in ice... Cleared up the drain holes a few months ago since water is what caused my booster to fail last summer. Sleet must have clogged up the holes and frozen over. Hopefully a defrost is all it takes!

 

Here's the pic...