Brake servo restricted

[p_aevans]

Quote

 

I had the same error appear (66 plate A4) on Sunday after returning from a 40 minute drive.  Luckily I was on my road and was able to park up within a minute of it appearing.  Didn't drive it again while trying to discover what the issue was which, having read the advice on this forum was the right thing to do.  Ordered my part from Audi parts direct (which appears to be the Audi main dealer in Cardiff), fitted it in less than 2 minutes and everything is fine again.

Cant thank the people on this forum enough.  The Audi dealer in Wolverhampton refused to admit they had come across this issue before and insisted that I needed to pay £144 for a diagnostic!!!.   The fact that you can buy knock off versions of this part on eBay, tells you there must be a market for them.  Audi should be ashamed of themselves!!

[Grovemack]

I am so grateful I found this forum. My Audi A4 (originally a 67 plate now in ROI) showed both the Brake Servo light and Start/Stop malfunction on Sunday after 2 weeks parked up (due to covid and further illness). I drove a few times during the week and made journey to family in NI, my own mechanic told me to drive on and it would be fine, thankfully found this forum. I currently still have just the display panel warnings and no orange or red lights, so I'm hoping and praying my <200miles won't have caused the further ABS issue and I'm going to try and get a part sourced tomorrow. I can't bare thinking about the ABS issue if I'd continued driving (hopefully caught it in time).

[Steve Q]

13 hours ago, Grovemack said:

I am so grateful I found this forum. My Audi A4 (originally a 67 plate now in ROI) showed both the Brake Servo light and Start/Stop malfunction on Sunday after 2 weeks parked up (due to covid and further illness). I drove a few times during the week and made journey to family in NI, my own mechanic told me to drive on and it would be fine, thankfully found this forum. I currently still have just the display panel warnings and no orange or red lights, so I'm hoping and praying my <200miles won't have caused the further ABS issue and I'm going to try and get a part sourced tomorrow. I can't bare thinking about the ABS issue if I'd continued driving (hopefully caught it in time).

Glad this thread has helped 🙂

[Ivan_W]

Another victim here. Just wanted to say thanks to everybody who has posted part numbers, advice on switching and help videos. I replaced my pressure sensor in 5 minutes at a cost of £80. Big savings on what Audi would have charged not to mention the potential massive costs involved had there been problems with the ABS system. Cheers all!

[p_aevans]

Hi all

After chaining the pressure sensor, has anyone else noticed the brakes feeling a bit spongy under braking?

[Shane12]

Hi all. Just had the Audi brake servo message myself over the weekend, along with auto stop start, brakes felt weird/clicky. Immediately drove back home and booked it in for Audi who have 2 weeks waiting time,  therefore ordered the part from here to do it myself. https://www.ebay.co.uk/itm/174926234420?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=-4l-DR-mS0e&sssrc=2349624&ssuid=l3OxFGC-SNK&var=&widget_ver=artemis&media=COPY .

 

This morning I thought to start the car up to see if the error was still present, and it wasn't, brakes felt fine (i didn't drive out). I was taking no chances and thought to wait to replace the sensor. For those who had the error appear intermittently (it did not stay permanently for me), was replacing the sensor the fix or was there more to it that was discovered with diagnostics?

 

Shane

Edited July 25, 2022 by Shane12

[PHB]

My fault was intermittent but I did not hesitate and changed the sensor which resolved all faults.

[CobboldSt]

Hello all,

Thank you all for providing your insight to this issue. I managed to change the sensor myself as per Simon’s helpful guide.

I test drove my 2017 A4 TFSI for a couple of miles and the fault did not reappear. The following day, upon startup, the fault reappeared; has anyone experienced this?

Ben

[Rich867]

1 hour ago, CobboldSt said:

Hello all,

Thank you all for providing your insight to this issue. I managed to change the sensor myself as per Simon’s helpful guide.

I test drove my 2017 A4 TFSI for a couple of miles and the fault did not reappear. The following day, upon startup, the fault reappeared; has anyone experienced this?

Ben

I changed the sensor a couple of months ago, it was the £20 one off eBay and not had the warning since. Stop start is working fine too since the change. Only thing I noticed was that my brake pedal was really stiff just after I changed the sensor but then went to normal after the engine was running which I put down to the pressure equalising in the system.

[Fruit]

I'm another victim of the servo fault. First time I had the message on the dash was approx. a month ago and because it said its fine to drive I`ve ignored it. It would be intermittent for weeks until this week when it would stay on all the time. I`ve done over 200 miles since the issue appeared for the first time. 

I'm really glad I found this forum, otherwise I wouldn't have thought much of the issue as it said it is ok to drive... I really got worried yesterday when I read stories of faulty ABS.

Luckily for me I have 7 days of the Audi approved used warranty left so as many people here suggested I`ve phoned the Audi roadside assistance. 

They didn't have any Audi technicians available today but they asked me if I want the AA  or the VW technician to come out. I`ve asked for the VW technician and he was at mine within 1 hour. 

When I said what the message on the dash says he knew straight away what the problem is, even before he spoke to me  he said he knew it will be the servo sensor. He didn`t have any spare ones but he said he will phone the local Audi service and will ask them if they have any in stock, but highlighted that if they don't, I should not be driving the car.

Luckily they had a few in stock so he went to get it and was back within 30min. Took him 1 minute to replace it and 15min to record it on their system and the job was done. 

Im so happy that even though I drove the car for a few weeks with the faulty servo sensor it didn`t cause  damage to the ABS unit. Of course the technician confirmed that all models form the VAG group so VW, AUDI, SKODA etc. that use this sensor have the same issue and he has seen a lot of cars where it caused damage to the ABS. 

 

 

[Timofei]

Hi all, thanks for such an informative topic, you saved me from spending a lot of money on a new abs module!

 

I was wondering if there is a difference between the sensors for vw/seat/Audi? As I see it, they all have the same number, but the seller marked them for different brands. (For example, the vw sensor is not compatible with Audi)

Is this just to optimise the search on Amazon, or is it better not to put a vw sensor on my Audi a4 17 plate?

 

vw  sensor:

https://www.amazon.co.uk/HouYeen-Booster-Pressure-Sensor-Arteon/dp/B09C64CHPP/ref=sr_1_3?crid=10A539N6OJD11&keywords=vw+brake+pressure+sensor&qid=1659187456&sprefix=vw+break+pressure+sensor%2Caps%2C46&sr=8-3

 

Audi sensor (out of stock):

https://www.amazon.co.uk/dp/B09C6435YV?tag=forsalecouk-21&linkCode=osi&th=1&psc=1

[kh904]

As long as the part number matches, you should be fine as the same sensor is used among many models in the VAG group (VW, Audi, Skoda).

The only questionable thing is the quality of a chinese part vs a genuine Audi part.

You can find a UK supplier from eBay quite easily for around £20 if you don't wan to spend £90 with Audi, and so far the reports on this forum seem to suggest that the aftermarket parts seem fine.

[jmac312]

2017 A4 Ultra...25000miles ....having not long been stung for a £1000 bill to replace the adblue management unit, now the servo brake sensor is lighting up our lives. Have read the posts on here, have ordered a replacement off eBay. Have gone for the cheap £19.99 one. If it works, then car is getting sold. Audi customer service are worse than hopeless....in fact, not much better than their cars these days 🙄

[FADEC]

“quality of a chinese part vs a genuine Audi part.”

Given that we’re all here having had to replace a quality Audi part after 3-4 years almost says it all!

[Magnet]

Hello Trevor,

Just wondering if this post can be flipped to always show the latest page (21 at the moment) rather than Post no.1 first. 
Many thanks and kind regards,

Gareth.

[jmac312]

Ok, have changed over the brake sensor.Now I have a new message 'DriveSystem Active. Please switch off engine" ! Brakes feel very spongy.

Help !!

[jmac312]

Havejust noticed that message only comes on when door open !. Bugger it, I'm going for a drive 

[jmac312]

Panic over....All seems to be fine. Does that make me a car mechanic now ?

[kh904]

I would highly recommend buying an OBDII scanner - The one that you can operate from a smartphone is pretty handy.

You can pick a VAG specific one for around £80.

It provides invaluable info/code reading and helps with diagnosis and clearing fault codes.

[TVR500]

just to add further perspective to this thread. I had the fault code the day I went on holiday for a week, as it said safe to drive, I completed the holiday covering 700 miles!

I found this thread on my return, ordered the part from a main stealer and fitted in couple of mins. fault codes cleared once fitted although I didn't get stop start fault code.

Driving 2 weeks since without issue, so far cost 90GBP for small flimsy part...B. I may have been lucky but also may have pending ABS issue. Audi should fess up to this one 3.5k is making me consider trading it....... moral is it may take more abuse than we think once registered

[John r1964]

I also had this same problem on my a4 67 plate 32 k my driveway is steep after stopping the car rolled back about 3 inches while i was applying handbrake warning came up . After driving it the next morning warning was still there i drove 20 miles to wirk and back and it had resolved itself hope this helps

[Magnet]

Thanks John,

So have you changed the sensor? 
Kind regards,

Gareth. 

[Rich867]

Four months on now and sensor seems ok.  I don’t think it is related but I am getting three beeps which sound like they are coming from the back seats/boot area.  No warning messages or lights on dash.  Only happens when the car is moving.

[kh904]

40 minutes ago, Rich867 said:

Four months on now and sensor seems ok.  I don’t think it is related but I am getting three beeps which sound like they are coming from the back seats/boot area.  No warning messages or lights on dash.  Only happens when the car is moving.

The beeps are a little concerning. I wouldn't ignore it just because you don't have a warning light on the dash.

Do you have access to an obd scanner to run a diagnostics? It's worth purchasing one (get a VAG dedicated scanner). Look up VAG scanner or FVAG, they are around £80 I think.

[Claudster]

Hi, 

After reading all  all the posts with regards to the stop start issue, here's an update. I have a 2017 A4 1.4 tfsi, just achieved 25000 miles.. had the stop start/servo issue so took it for diagnostic check. Result was, sensor and abs internal fault to a cost of £3300 to rectify.. Complained to the audi executive who has basically said hard luck, they no knowledge of it being a reoccurring problem and there would be no good will.. I have stated how unimpressed I am with his answer, and disappointed at how out of touch he is with what's going with regards to this fault, and will be passing it on to bbc watchdog to see what their findings are. In the mean time, replaced the sensor at a cost of £83 and the mechanic can get the abs rebuilt for £225 if it's required. The sensor has cured the stop start, but getting the warning with regards to the brakes on start up. Most disappointed with Audi to say the least, but I'm not going to let this go.. it's a major safety issue, and Audi don't care.