High pitch whine from top of engine on 2001 BMW 325xi

High pitch whine from top driver side of engine that goes up or down with the throttle of the engine. No service engine soon light on or other warning lights are on. Otherwise car runs fine. What is the cause of this noise?

Asked by for the 2001 BMW 325xi
Could be a VANOS unit, belt tensioner pulley, power steering pump, small air intake leak. It's not easy to diagnose a noise through the internet. The best thing would be to diagnose it with a stethoscope to pinpoint the exact location.

1 more answer
Sounds like a leak in the intake manifold or throttle body, maybe...