# Strange ABS \ Wheel Speed Sensor Issue?



## AndyTR32 (Jun 4, 2003)

2001 Audi A6 Avant 2.8L with 103k miles. 4 corners of new pads, rotors and fluid at 100k.

I have a strange problem when braking but it only occurs once I slow down to 7 MPH. Above that everything is kosher. Once the speedo hits 7 and I'm on the brakes I get a noticeable moan and push back / pulsating on the brake pedal as if ABS were kicking it. When it happens I get no ABS light or flashing ESP light. Once I slow down to about 3 or 4 MPH it goes away.

This all started last weekend after I had finished replacing my passenger side axle. My pinch bolt was seized so I had to drill it out. This morning I checked that ABS sensor and there was all kinds of metal shavings and rust (if you will) left over from the PB blaster. I thought perhaps the sensor was just dirty and giving a funny reading a low speeds. However, I cleaned things up as best as I could using compressed air and the issue still remains.

Any ideas? I was thinking about replacing the wheel speed ABS sensor but I'm not sure if that is my problem. If the sensor were bad, wouldn't the ABS light illuminate on the dash? I have no codes or warnings.

Thanks for the help,

Andy


----------



## greyhare (Dec 24, 2003)

Try unplugging the harness and flush out the connectors with contact cleaner.


----------



## codesniper1313 (Jun 6, 2009)

Jack the car up and check all four wheel speed sensors. Chances are one of them is busted to pieces from some debris that got into your spindle housing, and it's setting off the ABS system at low road speed. My friend had very similar problems with his R32. When you take them out, be careful not to break the plastic housing and also clean any magnetic dust you can off as well. If you find any one of them to be broken, I can almost guarantee that if you fix that, your problem will go away.


----------



## AndyTR32 (Jun 4, 2003)

codesniper1313 said:


> Jack the car up and check all four wheel speed sensors. Chances are one of them is busted to pieces from some debris that got into your spindle housing, and it's setting off the ABS system at low road speed. My friend had very similar problems with his R32. When you take them out, be careful not to break the plastic housing and also clean any magnetic dust you can off as well. If you find any one of them to be broken, I can almost guarantee that if you fix that, your problem will go away.


This was it. The Passenger side sensor magnet had become contaminated with a bunch of metal shavings from my previous drilling. Pryed it out, removed the metal and took a q-tip to the abs ring via the sensor hole in the hub. Put it all back together and problem solved. Thanks!


----------



## GTijoejoe (Oct 6, 2001)

AndyTR32 said:


> This was it. The Passenger side sensor magnet had become contaminated with a bunch of metal shavings from my previous drilling. Pryed it out, removed the metal and took a q-tip to the abs ring via the sensor hole in the hub. Put it all back together and problem solved. Thanks!


:laugh: I was going to mention that


----------



## codesniper1313 (Jun 6, 2009)

Awesome. :thumbup:


----------

