Brake servo restricted

[sorin s]

thank you KH904,

 

is it the one advised a few messages up? is it the MAP Brake booster pressure sensor?

 

 

[ian.f]

1 hour ago, sorin s said:

Hi all,

So glad I discovered this forum.

6 weeks ago, while reversing my 2016 A6 S line, my dashboard started to light like a Christmas tree, showing the following errors/faults:

- stabilisation control (ESC/ABS): fault!, see owners manual

- hold assist: unavailable

- main beam assist: system fault

- tire pressure: system fault!

- parking brake!

- Audi adaptive light: system fault!

- brake servo restricted. You can continue driving. Please contact workshop.

 

Since then, I probably did a further 500 miles and the car drives as normal...or at least I didn't feel anything suspicious with it; lights work ok, it brakes ok, steering wheel is ok, parking brake holds ok. 

 

Have any of you experienced similar? Do you have any advice?

Thank you.

 

I second, DO NOT DRIVE ANOTHER MILE! 
Yes, buy the sensor that’s listed in this thread and change it before you drive it again. I didn’t, and it cost me a fortune to replace & repair the subsequent damage. 

[kh904]

1 hour ago, sorin s said:

thank you KH904,

 

is it the one advised a few messages up? is it the MAP Brake booster pressure sensor?

 

It's the brake booster pressure sensor

 

[sorin s]

Thank you both for the valuable advice. Just ordered one from Amazon; will share my feedback after I fit it.

[P3N]

Good move Sorin.

i had the same message, drove 19 miles all the while the message only stated “ contact garage”. But my car totally failed. It cost me nearly £4k. I hadn’t found this forum 😩  Don’t move another inch until you have fitted the new part.  I now carry a spare in the car in case it goes again. 

[Peter Reville]

Bought new sensor from audi and tried to replace it myself. I was able to release the wiring clip but not able to release the clips at either side. Any advice?

[sorin s]

On 4/29/2025 at 9:31 AM, sorin s said:

Thank you both for the valuable advice. Just ordered one from Amazon; will share my feedback after I fit it.

Hi all,

2 weeks ago I bought the said sensor and installed it myself, however, the errors remained in the dashboard. Following that, I decided to take the car to a specialist and after they diagnosed it, it was found that the RHS front ABS speed sensor was faulty. After replacing it and running another diagnosis, it was found that the wiring loop for this ABS sensor was fried as well and that required to be replaced. In the end, it cost £ 525 to fix it. I attach the invoice to show the error codes, hopefully it will help others.

 

[kh904]

Ouch, that's made your wallet lighter. At least the ABS module wasn't bricked!

Any idea how the wiring loom got fried?

[sorin s]

What they said was that when the ABS sensor failed, the wiring loop got shorted... don't know what to say, I don't really trust garages/mechanics  🙂

[Forgot my password]

Thanks for the above responses.

I tried again to remove the sensor with the help of youtube videos. I was successful this time and was able to fit the new part myself. Fault message was removed automatically as suggested by the video and all is good. I did not have to get a diagnostic test. I understand Audi is aware of this common problem and have since modified the part. I hope this is of assistance to anyone having the same issue.