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1997 Audi A4 Quattro 1.8T

So this has happened twice within the last month or so…While driving my front passenger side and rear driver side brakes basically locked up to the point where I couldn’t drive and the rotors and pads got red hot…now my brake pedal goes to the floor and theres no brake there…Is this a master cylinder issue or possibly the ABS control unit? Any help would be greatly appreciated

Your Audi may have a split system so that the right front and left rear are activated by one part of the master cylinder and the left front and right rear are activated by the other side. If this is the case, then there may be a problem with the master cylinder. You lost the brakes because the brake fluid boiled.

There may be a problem in the antilock braking system. I had a Ford Aerostar that had antilock brakes on the rear wheels only. A valve was gummed up and if the antilock brakes came on, the rear wheel brakes wouldn’t release.

If your car has a diagonal split braking system, (I don’t know Audi cars very well), you may have a master cylinder problem.

well two of my ABS wheel speed sensors are broke so the ABS doesn’t work but it had been like that for a while prior to this issue…I was hoping the master cylinder but I have a bad feeling about the ABS control unit which both lines that come out of the master cylinder go into and then 4 lines come out of that??

When was the last time the brake fluid was replaced?

not in the two years that I have owned…so I think I’m going to get all new rotors, pads, master cylinder, and change the fluid and hope that takes care of it because the ABS control unit is ±$1,000.