High-pitched noise

[nermal]

I've noticed a high-pitched whistle/~squeaking that only seems to occur while the car is level and in drive. It's noticeable at idle and low speeds and seems to go away (after a second or so) when put into neutral. It's not very loud (yet), but I'd rather head off an issue than try ignore it.


It's still there with the A/C and head unit off - was originally thinking speaker hiss or fan whistle. Also, there doesn't seem to be any noticeable difference with windows up or down.


I'm thinking PCV, diverter valve, intake or vacuum hose leaks etc... but it's weird how it goes away in neutral or if on an incline (it seems) - though perhaps that could just affect engine load.


The car has been tuned (ECU & TCU), but I've only just noticed the noise in the past few days.


Any ideas/advice?

[nermal]

It kind of went away for a day or so, but is back now. The whistle seems to happen when take my foot off the accelerator pedal and goes away when accelerating (and the clutch is engaged).

[Vedi]

A bit hard to narrow down, this Passat forum post (https://www.vwvortex.com/threads/whistling-noise-when-not-accelerating-and-at-idle.4872401/) has a few ideas to check.

A few people found it was the Crankcase Vent Valve (as you predicted), which the Arteon also has. Let us know how you go.

[nermal]

Awesome, thanks - I'll get it checked out. Doesn't sound super-serious, though may also explain the rough idling at times.

[nermal]

Took it in to VW and they couldn't replicate it. As I was leaving I heard it, so called them back out. They couldn't hear it from outside the car, but brought their "Squeaks and Rattles" Engineer out who heard it straight away. He pinpointed to the adaptive suspension (confusingly named ACC). Apparently, it's common on the Golf R's and so far no fix from VW yet.

So, nothing too serious.. I'll try ignore it and if it happens to let go, then I might consider some coilovers.

On a side note - this guy has an amazing ear. He diagnosed my lose brakes straight up after a brief drive around the block... I may have to buy an hour or so of his time to pinpoint all my annoying squeaks and rattles - especially after the upgraded sub is (finally) transplanted and doors and dashes are rattling more than usual with the bass