The other day I jumped in my 02 a6, I let it warm up for about 10 minutes. Then the esp light came on, before I shifted out of park. Turned off the ignition and restarted. I was driving for about 10 minutes before I got on the highway. At about 50 mph the brakes slammed on by themselves bringing the car to a screeching halt, while cars swerved around me. I got off the highway and the esp light was on, but it felt like the abs was engaged and I was not pressing the brake. What's going on?! Thanks for the help in advance.

 

I had similar problems with my 02 A6. I was driving on the highway, and all of the sudden front/right wheel braked, causing the car to pull to the right at high speed.

In an attempt to resolve this, I replaced a an axle sensor underneath back seat. Unfortunately, this wasn't a problem. What I think resolved it, was to unplug connector from ABS controller, clean it with compressed air and spray it with electronics contact cleaner, then place back securely into ABS controller. Since then I had no issues with brakes.

Also, good thing is to pull codes from the ECU, to see if it did not loose contact with ABS controller, then check codes on ABS controller itself. In my case I did not have any codes thrown on either controller.

Hope this helps.

 

That's exactly what happened, it felt like the front right wheel. How long have you been driving the car without another incident, since cleaning the abs controller connector? Thanks again.

 

It's been like 2 years now without issues.

Also worth to add, I used have the ESP light go on when making right turn on intersection, and brake engaging on front/right wheel as well. I could not figure out why it was happening when only making right turn. I thought of the speed sensor, but I never got any codes for it in ABS controller.

 

That's good to know, I suggested to my mechanic that it was a sensor and he says no. Instead he tells me to change the brake lines. But I'd like to know why is the esp light come on if its a possible abs module or connection problem? Thanks again.

 

ESP light will come on if there is an uneven wheel rotation, caused by driving on snow or gravel, for example. This is part of ABS control.

I forgot to add earlier, the braking system should be flushed from old fluid. If the fluid has never been changed since 2002, then most likely it's worn out. I flushed the the system in my car, and what I saw was just horrible. Th old fluid was black with some particles floating in it. After re-flushing with new fluid, brakes are perfect. I doubt the brake lines need to be replaced.

 

What do your brake lines have to do with your car locking up the brakes? Maybe I should say, what would have to be wrong with your brake lines to cause your car to lock up the brakes?

I think you need a new mechanic.

My guess is your stability control engaged for whatever reason and stopped the car. Something told the car it needed to brake the right front wheel, so it complied. Now you need to figure out why.

 

The mechanic has had the car for 4 days , and has come up with nothing. Today I will switch mechanics.

 

funny my car did the exact same thing on the same wheel .. locked up the front right on the highway .. by the time I got to the exit i was out one rotor, a set of pads, a melted caliper seal and bellows also melted all the paint off the splash shield.

had the ABS module rebuilt and all is good now .. well .. after fixing all the other stuff..

 

That's a new one I've never experienced (yet). Doubt this is your problem but, if a brake hose has collapsed internally, it will hold pressure in the caliper. As it heats up, the fluid expands and apllies the brake more, which causes more heat, more pressure, etc. However, it wouldn't be sporadic, it'd happen all the time. A fault in the ABS hydraulic control unit could be sporadic and cause the same problem if it wasn't allowing fluid to expand back to the master cylinder reservoir.

Are you sure it's just the rf brake yet? I wouldn't be too hard on your tech, if the problem isn't present currently, any diagnosis would be a wild guess if you understand where i'm coming from. Kind of like "the engine wouldn't start" but now it starts and runs fine with no fault codes stored in memory. It could be any number of causes. I'll do some checking into any common problems and see if I can find any more info for you.

Part of the Audi maintenance is to change the brake fluid every two years, regardless of mileage. Don't forget, they use DOT 4 fluid. Actually ANY make of vehicle should change the fluid every two years.