I’ve just taken my MK3.5 VRS petrol for a service at the main dealer. Car is at 85k and has been serviced on time every year since its March 2020 mfg date. Did the brake fluid and gearbox last year. 
 

Car has been perfect until today after picking it up. Now I’m hearing a low pitched whining/humming noise while the ignition is switched on. It doesn’t increase at revs - stays the same. Tried switching off AC/audio and the sound persists. 
 

This most recent service was a big one and they changed spark plugs etc. workbook doesn’t say anything that looks out of the ordinary and it’s just passed MOT today too. So I am pretty annoyed at this new sound. I called the dealership and they told me to bring it back next week which I will do. 
 

in the meantime wondering if any of you true experts can provide some insight?

 

cheers

Can you tell everything that was done in the service?

Word for word from the invoice - 

 

filterelem

drain plug

od. Filter 

airfilter

spark plug g2a

castrol ll IV 0w-2

1 hour ago, Lalapotty said:

Tried switching off AC/audio and the sound persists

Did you try to turn the fan completely off?

yes. Wish it was that simple!

Fuel pump in tank that you either didn't notice before or maybe is louder because they change a filter.

 

There was alot of filters charged on that list. Was one a fuel filter?

 

Where is the noise coming from?

Inside, engine bay, underneath?

 

Is it when engine running or just ignition on?

I’d be surprised if it was a new filter? I have no idea if one of them was fuel...

 

noise is inside the car, when the ignition is turned to on but even with the engine off. When I’m driving It cuts out briefly when the start stop activates then comes back again..

Edited 22 February, 20251 yr by Lalapotty

19 minutes ago, Lalapotty said:

When I’m driving It cuts out briefly when the start stop activates then comes back again..

By activation do you mean when the start stop shuts off the engine? And sound comes back when engine turns on again?

 

I did also think about the fuel pump but with the job list there should not be reason for any changes to it and also I dont believe anyone should notice fuel pump sound while engine is on. And op has petrol car so I dont believe fuel filter has been changed, also not listed.

 

With the job list only reasonable cause would have been that something dropped into the cabin blower during pollen filter change but that is also ruled out already. Anything else should not have required any dismatling or so that could lead to cause extra humming. Of course they might have done whatever random stuff..

Edited 22 February, 20251 yr by Skodaudi

Yes when the engine cuts out the sound goes away and then immediately returns when it starts again. 
 

Thanks for your efforts! Going to see them on Monday and I’ve already convinced myself they’re going to fob me off. I was so happy with the car until now 😔

Try to see if you can determine where the sound is coming from.  The usual thing is: if there is a mysterious sound, then make a recording of it and show the service advisor, so they don't fob you off and say "sorry sir, no fault found, that will be £190 for diag pls"