Q7 Brake servo restricted start/stop system fault function unavailable

[SG77]

Hi All, has anyone had this?
Still can drive, feels like ABS is constantly on when breaking.

Can anyone advise whether it’s a simple fix and can I do it DIY.

many thanks

[Crasher]

A fault code scan is an urgent priority here, the servo has a small easy to replace pressure sensor (usually part number 5Q0 906 207 and £88.74) on the vacuum pipe and these fail. When this happens the ABS pump takes over servo duties and very quickly burns out the unit which is around £3K and not a quick job.

[budgie55]

I just had same fault this morning on a 68 plate Q7, does anyone have detail as to how to swap out as the dealerships local to me are 3-4m wait time just for diagnostic (what a joke!)

[Crasher]

It is so easy that it is ridiculous, open the hatch above the master cylinder, remove sender and fit new one, a skilled tech could do one in 30 seconds including opening the door, pulling the handle and opening the bonnet.

[budgie55]

Thanks Crasher, your info plus a quick YouTube proved fruitful. All now changed, breaks working and warnings cleared. My local dealer 3 month appointment cancelled (would have been royally screwed without this forum around ABS servo warning and how to fix, thanks all!)

[inchshort]

Just had a brake servo fault come
On the dash…£140 for diagnosis from Audi and then the fitting of the part. I will try and change it out myself first.

The symptoms are, the brakes work but when the pedal is pressed, it presses in and then there is resistance and then presses in further, almost in 2 stages of braking…I hope it is the sensor….any further suggestions?

[Crasher]

Code read or change the sensor.

[jldiablo]

I had the same issue when I was on holiday in Wales a year ago, the car was drivable but braking felt really weird. I couldn't get the car booked in anywhere nearby at the time and couldn't get the parts quick enough to DIY it, eventually the ABS pump failed after a couple of days (red warning saying stop driving immediately). Car had to be towed away to dealership by Roadside Assistance, and a new ABS pump was needed. I was lucky that extended warrenty covered everything, and I was given a rather nice courtsy car for the entire time. Have to say, great service from Audi on the issue (roadside and dealership) which made me decide to keep the car for a bit longer, and will probably stay with the brand for my next car.

I believe the video below shows how to DIY it, and it looks really straightward if you can source the parts. Go get it sorted ASAP to avoid the hassles of having to deal with a broken ABS pump.. it will break if you keep using the car
Q7 Brake servo restricted start/stop system fault function unavailable Brake Booster Pressure Sensor - YouTube (https://www.youtube.com/watch?v=iI7Mr59Bg1U)

[Crasher]

If I owned a car with this system (which I refuse to do) I would carry a sensor in the glovebox to avoid a breakdown and £3K+ bill.

[jldiablo]

If I owned a car with this system (which I refuse to do) I would carry a sensor in the glovebox to avoid a breakdown and £3K+ bill.
This is so true!

[webego]

If I owned a car with this system (which I refuse to do) I would carry a sensor in the glovebox to avoid a breakdown and £3K+ bill.

Which system is this? I'm looking for a Q7 S-Line at the moment and would like to avoid any troublesome systems where possible.

[Crasher]

Most have it now, even the A4.

[webego]

Thanks, good to know. As you say, sounds like a no-brainer to carry a spare around with you.

[webego]

Is there a particular preferred brand for this part? Which one is OEM? Prices range from around £20 to about £65 for a Vemo.

[Crasher]

The typical genuine one, 5Q0 906 207, is £88.74, would you want to risk a £3k ABS unit for a cheap sensor?

https://digital-assets.tecalliance.services/images/3200/86e4d6f1807b154da3f2f3878b46c9bb06b90443.jpg?ver=3 .72.0.2fb453d7fe

[webego]

The typical genuine one, 5Q0 906 207, is £88.74, would you want to risk a £3k ABS unit for a cheap sensor?

Absolutely not! So that one looks like the VEMO. Just checked again and it has gone up by £7 since yesterday lol.

[ragebe]

It is so easy that it is ridiculous, open the hatch above the master cylinder, remove sender and fit new one, a skilled tech could do one in 30 seconds including opening the door, pulling the handle and opening the bonnet.I can't see the hatch above the servo, on my 2016 4M. It's definitely not in the same place as that one in the YouTube video.

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[ragebe]

I can't see the hatch above the servo, on my 2016 4M. It's definitely not in the same place as that one in the YouTube video.

Sent from my SM-G965F using TapatalkAnswering myself. Having looked in daylight, I've located the servo hatch and can easily see the servo.
However the fault has cleared, which suggests a connection issue or perhaps the sensor has an intermittent fault.
It looks a simple and easy job to change it but I can't seem to locate the part online. Anybody with a pointer towards it, please sing out.

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[ragebe]

Audi/VW Brake pressure sensor 5Q0906207 (https://www.audipartsdirect.co.uk/product/audi-vw-brake-pressure-sensor-5q0906207-5q0906207)

Is this it?

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[Crasher]

I don't watch "look at me" nasassistic YouTube videos, mostly ones about blowing up Russians. You have to remove the wiper arms and plenum chamber cover, when removing and refitting, take great care not to crack the screen... don't ask! :zx11:

[ragebe]

Well, I fitted said sensor successfully.
Followed the video (more or less).
> removed sensor cover.
> used screwdriver to unclip the two clips, holding the sensor body in place.
> eased the sensor off the servo (escape of air)
> then removed plug from old sensor and fitted plug in new sensor and pushed grey-clip home (important)
> then took a few attempts to push sensor into position on servo, which led to me dropping the sensor a few times but fortunately, being attached the the grey-clip, meant retrieval was easy.
> sensor firmly in place
> started car.
> this wasn't as quickly as normal, perhaps because the servo was empty of air. Car started, after some seconds of waiting.
> braking then operated normally, drove car for 60 miles to test.

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