Having some ABS issues with my 99.5 since I bought it. ABS kicks on at the end or a stop or slow speed stops. Had it scanned and the shop said the sensors were all reading OK however front right was lagging. So I purchased (2) new sensors online. Installed the rt front. No change, I figure to install the left front. Still having the problem. Both front tone rings look good, no cracks. The left rear sensor was also replaced just before I bought it. Just ended up pulling the connector on one of the sensors to disable the ABS so it didn't keep doing it.

I am at a total loss now. Unless it is the only not new sensor rt rear or a cracked rear tone ring I can't figure it out.

Any suggestions. I am ready to throw in the towel and take it to a shop or give up and leave it as is with the yellow ABS light glaring at me all the time.

 

Hey I am sort of in the same situation you are in with my a4 b5 quattro 1.8t. I had a bad front abs sensor and replaced both of the front and my abs problem went away. now I have a abs issue again where my abs light comes on and brake light flashes beside it and it beeps 3 times. Now I did have a bad wheel bearing on the front as well, could that cause my new abs sensor to go bad? Also does anyone know the rear abs sensor part numbers? That is what I plan on replacing next but can not find a solid answer on what part numbers are.

As for your issue I would say replace the one sensor you have left and see if that is the issue.

 

Ahhh this is such a fun issue. I spent a lot of time getting the ABS system on my car to work, as it was nonfunctional when I bought the car.

First off, I gotta say that using the appropriate scanning tool like Ross-Tech VAG-COM is one of the most useful things for a job like this. While driving (if you have a laptop) you can have it show you the readings from each wheel speed sensor (ABS sensor) and find which one isn't reading properly. Then diagnosis is easy from there on out.

For me it was a bad ABS module, then a cracked/split front tone ring, then both front sensors were damaged, and finally one of the rear sensors wasn't pushed in far enough.

 

The distance from the sensors to the rings is important too. Too close and the ends will get shaved off and be permanemtly damaged; too far away and it won't read anything.

 

I need to get a vag com. I tested different sensor air gaps. Starting a 3mm and ending up at about 1.2 - 1.5 mm. Made no difference. I'm not throwing any codes the ABS just activates at low speed when I hit 5 - 10 mph until fully stopped. My guess is that one of the sensors, proably the one I haven't replaced yet is dropping off or of the tone rings are cracked.

 

I used to get that too - does the ABS cause a strange musical tone and make your brakes nearly non-functional at those lower speeds? During drives when I had that issue the ABS module would eventually realize there was a fault and flash an error on the dash.