Brake servo restricted

[ian.f]

Concurring with the above posts. 

I’m astounded at Audi’s behaviour completely through the ownership of my A4. 
It cost me £16,000 in 2019. I’ve had so many issues with it, like this ABS issue, ECU failures, I think I’ve replaced every sensor under the bonnet, AdBlue sensor failure, etc, etc. I’ve spent £9k to date and I’m currently looking at another £1.2k on having to drop the gearbox out to disassemble it to get at, wait for it, another sensor!

Audi have refused to acknowledge any inherent issues with the B9. All they say is “book it in for a diagnostic” then quote me crazy prices to fix things I can do myself or others can do at half the cost.

This was my first Audi, and will be my last VAG vehicle.  

[kh904]

Ouch! You've had particular bad luck with your A4!

Mine hasn't been too bad in terms of non-wear and tear repairs, but then again i don't do many miles (around 3k a year)!

[MarkH13]

2017 RS5, and had the dreaded brake servo and stop/start warning messages this afternoon...

Luckily my car has an extended warranty, so I've called Audi Assist, and someone is on their way - hopefully they'll be able to fit the sensor, and there will be no damage to my ABS! 🙏

[kh904]

I'm sure you will be okay since you've called Audi Assist as soon as you got the message (assuming you haven't done many miles and hard braking since).

[MarkH13]

Thank you, I do hope so 🤞

[P3N]

Good luck Mark.  Let us know so we can enjoy the relief.  I heard that Audi Assist carry this particular part as standard practice now.  Very telling that 🙄

Edited September 30, 2024 by P3N

[MarkH13]

Thank you very much - unfortunately it wasn't as simple as I hoped, the diagnostics came back with a bunch of errors (including ABS!) so they're having to take the car to Audi to get it all checked out... A bit frustrating, but at least Audi Assist provides a courtesy car, which I didn't know, so I'll still be mobile 😃

[GreyknightV6]

Had the dreaded warning appear on my S4 last week, so stopped using it and took it to the garage.

They advised me to contact Audi to get it done FOC, but Audi were having none of it.  Garage diagnosed it as the brake booster, what the going cost for the repair?

[ian.f]

1 hour ago, GreyknightV6 said:

Had the dreaded warning appear on my S4 last week, so stopped using it and took it to the garage.

They advised me to contact Audi to get it done FOC, but Audi were having none of it.  Garage diagnosed it as the brake booster, what the going cost for the repair?

Are they sure it’s the booster? Not heard of the booster itself going bad. Have you had the sensor changed? If not, try it yourself. It’s really simple if you can diy a bit. The sensors are about £20ish when I last checked. Am replacing mine again soon…it’s part of my yearly routine!!

[Sid2020]

Il shed my insight on these sensors as I deal with vehicle electronics a lot. The sensor on the servo is more of a safety device that has been used for years and often puts faults in stop/start systems and cruise controls systems, the restricted brake performance is the vehicles ecu reducing the limits of the abs pump/ module. It is worth buying a new sensor from the likes of eBay and fitting yourself. No coding required and system will reset after a certain amount of driving, sensor replacement will not involve any fluid loss so is a DIY job 

[gtay]

Had this message appear on Friday night. Thankfully having read this tale, I knew exactly what to do - ordered one off eBay £14.99 it arrived today and was fitted tonight in less than 5 mins - great forum.   

[Sid2020]

49 minutes ago, gtay said:

Had this message appear on Friday night. Thankfully having read this tale, I knew exactly what to do - ordered one off ebay £14.99 it arrived today and was fitted tonight in less than 5 mins - great forum.   

Great outcome 

[P3N]

Agreed, well done 👍

[Steve Q]

17 hours ago, gtay said:

Had this message appear on Friday night. Thankfully having read this tale, I knew exactly what to do - ordered one off ebay £14.99 it arrived today and was fitted tonight in less than 5 mins - great forum.   

Really glad this thread and forum helped 🙂 it's feedback like this which is greatly appreciated ☺️ 

[mike.t]

Thanks for Everyone who’s posted on this topic,   Same issue apart from my car is used every day.  I ended up buying one from an Audi dealer £100.  As I had a week of long journeys, poss could have risked it and waiting for the e-bay delivery but I’ll never know.   Anyway in my head I’ve still saved £150 fitting it myself instead of thinking of the £80 difference of the same part.   I still ordered one from eBay and now I’ve a cheap spare.  Thanks again for the advise I can’t imagine there are too many sensors on a modern car you can get to so easily 😊😊👍

[Sid2020]

6 hours ago, mike.t said:

Thanks for Everyone who’s posted on this topic,   Same issue apart from my car is used every day.  I ended up buying one from an Audi dealer £100.  As I had a week of long journeys, poss could have risked it and waiting for the e-bay delivery but I’ll never know.   Anyway in my head I’ve still saved £150 fitting it myself instead of thinking of the £80 difference of the same part.   I still ordered one from eBay and now I’ve a cheap spare.  Thanks again for the advise I can’t imagine there are too many sensors on a modern car you can get to so easily 😊😊👍

Sometimes you get what you pay for so I wouldn’t think about the part prices but as you say, makes you feel good when you do the job yourself 

[Sid2020]

So my car has suffered the same fate, servo sensor from Amazon for £13, looked 100% identical to the removed one, same plastics and markings except the Audi logo had been scratched off which is quite common on aftermarket parts if there made by the same supplier Audi use. Bargain 

[Karlos0403]

Has anyone had this issue on a 2019 Q5 TFSI

[Sid2020]

7 minutes ago, Karlos0403 said:

Has anyone had this issue on a 2019 Q5 TFSI

Pretty sure it’s the same part number across most the range so will affect all models 

[Karlos0403]

Thanks I’ll get it sorted today

[Sid2020]

This is the Amazon seller I bought mine from and appears to be manufactured on same line as the Audi sold ones. materials and markings matched up and even just had the Audi logo marking scratched off. The One on the listing photo  looks like cheap rubbish but that’s not what they sent 

[GreyknightV6]

Thought I'd loop back on this.  Garage replaced the sensor, issue went away!  Brake booster was a red herring.

[Karlos0403]

I replaced it myself and solved the issue. What I did find was a million sycamore seeds under the panel there

[sorin s]

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.

 

[kh904]

Regarding the Brake Servo restricted warning light - if you haven't replaced the sensor, DO NOT DRIVE IT!!!

The braking may feel normal, but you run the risk of triggering the ABS cycles enough times that it will brick the ABS, leaving you with a VERY BIG bill!

Just buy the replacement sensor (OEM or an aftermarket) asap and fit it yourself - it's dead easy to do (1/2 minute job)!

Edited 6 hours ago by kh904