Strange Whining/Whistling Noise
 

I'm having a strange problem with my 2005 A8 L 4.2

When the car is idling at a light or in park there is whining/whistling sound coming from the engine. I can't hear it when the car is driving. If the car is in park or idling and as I'm turning the steering wheel in either direction it stops then it comes back as I stop moving the wheel. Anybody experience this problem before? I checked power steering levels seem good but the fluid does smell burnt. Thanks in advance.

First thing I'd look for is a vacuum leak, but that may not be it if it's presents itself with wheel movement, or lack thereof.

If the fluid smells burnt, that doesn't sound good.
I half expected to see a time based replacement for the PS fluid on the maintenance chart but there isn't one.

Any DTCs showing up in VCDS AutoScan ?