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So I picked up my 2011 Audi A4 Avant last week, and it's been an extremely good car. The car has followed service intervals, and has current gone about 86,000 km ≈ 53,000 miles.

The other day, I got a warning message on the center driver display. However, the message disappeared as fast as it came and I was unable to read what it said. I drove home, but noticed something was up with what appears to be the brakes.

Now, the problem comes and goes a lot, but it's almost certainly there every time I drive. What happens is that I occasionally hear a kind of tick in the wheels, and I can feel almost like a gentle poke on the pedal. When I brake (lightly seems to provoke it the most) it makes a scratching noice like "Brrrhmmm" and I can feel it in the brake pedal. The sensation is almost like a reduced ABS experience.

Often at the same time of driving (not exactly the scratch moment), but not necessarily - I get a warning message that reads "parking brake malfunction", followed by the stability system and ABS disabling.

These come and go, and sometimes I'm able to drive for an hour without any warning.

I may also add that the tick when driving normally is often followed by a slight "hiccup" in the car that you can feel. Almost like a little tap on the brakes

Never the less, I appreciate any tips or help with this at all! Thanks in advance!

Best Regards, Erik

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I've found the cause at the Audi dealership. It's an RPM sensor in the ABS system that was worn out and has been wearing out the wheel bearings as a result. The sensor has to be replaced, and most likely the bearings as well.

  • Are you sure the wheel speed sensor was wearing out the bearing? I ask because the sensors I'm familiar with are Hall sensors that should have no physical contact with the wheel bearing or shaft, so I find it odd that the wheel bearing would be adversely affected. – Zaid Sep 10 '17 at 19:40
  • @Zaid As for the actual installation and whether or not they are in physical contact I'm not sure. The bearing turned out fine though, it wasn't damaged by the sensor so it appears you are correct. – Erik Sep 10 '17 at 20:05
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Parking brakes, when not used for a long time can get temperamental. This is mostly due to rust building up on the components and road vibration moving things around slightly.

Pull hard on your parking brake and then release it. Repeat this a few times. Maybe all that happened was you bumped against the handle and it's slightly engaged, like 1 click. The computer may be freaking out and disabling traction control and ABS to prevent them from causing you a loss on control.

  • I can't comment on the use of the parking brake as I've owned the car for merely a week, but judging from the car being in neutral with e-brake engaged when I first test drove it - I can only assume they used the parking brake. – Erik Mar 4 '17 at 17:59
  • You're saying that I may have bumped against the handle and having it slightly engage. Do you mean that it might be causing the hiccup? I find it strange because I always keep both hands on the steering and far away from the park lever, so I'm definitely not pressing it while driving and the hiccups have happened several times. So I should forcefully pull the lever? Could you please elaborate on this? How sensitive is this switch? – Erik Mar 4 '17 at 18:00
  • There's a switch that tells the computer if the handle is all the way down, just so it knows. By "pulling" the parking brake, I mean apply it fully. You don't need to bump it while driving to engage it, you may have bumped it one time, maybe a jacket or a bag strap got slightly snagged on the handle one time. :) – tlhIngan Mar 4 '17 at 21:21
  • Not quite sure we're on the same page :P you're aware the car has electronic parking brake? Just so we don't confuse words and such :) It's just a little button flap – Erik Mar 4 '17 at 21:38
  • @Erik I've never seen electronic parking brakes. Sounds like a bad idea to me, but whatever. Your error warning about "parking brake malfunction" makes more sense now. A quick test you can do is apply the parking brake, put the car into gear and see if the parking brake is holding. Repeat that a few times, and make sure the parking brake actually gets released after each try by putting the car into gear and letting it creep forward. Don't step on the gas while doing this, just idle the car forward, with the parking brake on and then off. – tlhIngan Mar 5 '17 at 0:50

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