2009 VW JETTA - ABS System Alarm - But only while driving it in one place

Maintenance/Repairs
1

Hi all! My first time posting here at CarTalk.

I have a 2009 VW JETTA. I have experienced my ABS alarm lights and sounds coming on in the past few months, twice while driving at speed in a curve and braking. Stopping the vehicle, turning it off and back on clears the errors, checking with my ODBII reader once I get home finds no errors.

Where this has occurred is a rather odd exit off of I-70 to Wadsworth Blvd., you are exiting at pretty good speed from the Interstate, curving to the right, then to the left and pretty much braking the entire time, and going into a slight bank. You can feel the increase in G’s as you make this exit. I have also driven the exit and greatly reduced my speed and level of braking and the issue with the ABS does not occur. My local dealer is at a loss to find or explain what is occurring.

My questions are, is there something seriously wrong with my braking system (ABS), if there is, what is it, if there isn’t, why does it do this only under the conditions that it is occurring?

Thanks much,
Patrick

2

Your generic OBDII code reader isn’t capable of pulling ABS/Air Bag codes. This requires a special ABS/Air Bag scanner.

The ABS light coming on may be the early signs of a worn out wheel bearing. The bearing/hub assembly also includes the tone ring for the wheel speed sensor. If the bearing is worn, and the tone ring becomes misaligned with the wheel speed sensor, this can cause the ABS light to come on.

Tester

3

Thank you, I would assume that a dealer, or garage would have the scanner and it would tell what the error is?

Patrick

4

Good advice above. ABS problems are often due to wheel speed sensing errors, so the sensors are a possible culprit. One other thing you might do is verify the tire pressure in all four tires is in the range it should be (see the owner’s manual), and as close as possible to the same in all four tires. When you go around a curve at higher speeds, and brake, the tires on the one side get a lot of pressure on them, so they may be flattening a little too much, which – if the tires are a little low on air or are low on that side compared to the other side – changes the wheel speed more than the ABS expects it would.