Hi All - strange one this……

I have a 2017 A4 B9 Allroad 2.0 TDI Sport (for around 1.5 yrs now) - a sound which I’ve puzzled over since purchasing is;

when starting a new journey from cold & first time of pressing brake pedal, I can discern a faint buzz (almost like the sound of an electrical ‘pump’ for say wiper washers) for 2 or 3 seconds. Subsequent brake presses will repeat this sound & this can continue for up to around 15 minutes of the journey (then even for the rest of even a long journey it does not happen again). Brakes work well by the way. 
I’m thinking this maybe an electrical vacuum pump for servo assistance / does anyone know if this model has an electrical vacuum pump?? 
I tried to research to no avail (only found possibly that the vacuum pump is mechanically driven 🤷)

Any other ideas or help much appreciated!

No idea. I have same car but in 3.0TDI V6 guise. Must admit, I've never heard this particular noise. Brakes are very good and much better than the B8 2.0 TDI version I had before. There's an electro-mechanical handbrake, but you'll be familiar with that noise with releasing and engaging handbrake, plus fuel pump priming prior to ignition. I know the B9 suffered from brake pressure switch issues. If you get this warning on the dash, then do not drive it, even if the car says its safe to do so. There's a real chance you'll screw up the ABS pump, so leave the car exactly where it is. The offending part is a few pounds from the main dealer. Only real way to check the car is VCDS scan. It will check brake modules for any logged errors.

Edited December 11, 2025Dec 11 by spartacus 68

1 hour ago, Basher said:

Hi All - strange one this……

I have a 2017 A4 B9 Allroad 2.0 TDI Sport (for around 1.5 yrs now) - a sound which I’ve puzzled over since purchasing is;

when starting a new journey from cold & first time of pressing brake pedal, I can discern a faint buzz (almost like the sound of an electrical ‘pump’ for say wiper washers) for 2 or 3 seconds. Subsequent brake presses will repeat this sound & this can continue for up to around 15 minutes of the journey (then even for the rest of even a long journey it does not happen again). Brakes work well by the way. 
I’m thinking this maybe an electrical vacuum pump for servo assistance / does anyone know if this model has an electrical vacuum pump?? 
I tried to research to no avail (only found possibly that the vacuum pump is mechanically driven 🤷)

Any other ideas or help much appreciated!

Hi its probably the brake pads warming up thats why it stops after a while.

STEVE.

 

Thanks Spartacus 68 & Stevey Y

yeah as I say it’s a strange one. Definitely nothing to do with e handbrake / or pads warming (even the slightest blip on the brake pedal produces this ‘motor / pump’ whatever it is noise - very much like a windscreen washer pump) which repeats with subsequent brake use, for a while

anyone know if there’s a electric vacuum pump version of this car??

If the car is re-started fairly soon after a drive, say a short stop at a shop, & then drive off THIS DOES NOT RECURR 🤷 (makes me think sufficient servo vacuum is already stored)

Just concerned something isn’t right - & would like to understand or get it fixed (especially as its brakes) & I have another 6 months ‘warranty’

Thanks All

One more try……

anyone know if there’s a electric vacuum pump version of this car??
 

thanks & I’ll try other forums if no one can advise

Your description sounds very much like the electro-hydraulic servo I had on one of my cars, (I can't remember if it was the A3 or the Granada), which made a faint sort of buzzing sound. It lasted only for 15 seconds at most, and stopped as soon as the pressure reached its set point.

Thanks cliffcoggin - that gives me a little confidence that I might be on the right track.

Did your car exhibit the repeated sound on subsequent brake pedal presses for a short while?

Whenever the brakes are used the reservoir pressure is depleted so the pump recharges it. It should only take a couple of seconds and be inaudible while driving. If yours takes longer or is noisy it probably needs overhaul.

Thanks again cliffcoggin - that was the theory I was following 

I was hoping someone could confirm if my car has an electric servo vacuum pump (as I’ve been told it does not & uses the cam driven type)

33 minutes ago, Basher said:

Thanks again cliffcoggin - that was the theory I was following 

I was hoping someone could confirm if my car has an electric servo vacuum pump (as I’ve been told it does not & uses the cam driven type)

Hi the servo vacuum pump is indeed the cam driven type, various manufacturers have tried the electronic type but gave up as they were not reliable which I can see as long as the engine is turning you have vacuum unless your one has a leak on the seal between the unit and the engine.

Steve.

Thanks Stevey Y for your comment

Hmmm well back to what the noise could alternatively be then - definitely linked to brake pedal press after car sitting for a while/overnight, & only exhibits for first 5 - 15 mins of a journey 🤷‍♂️

This isnt a loud noise by any means / just that i can discern it (I'm usually very aware of odd noises in a car)

Any more thoughts anyone?