High Pitched Whistling Noise from 2007 Volkswagen Passat 2.0T

both answers could be right,odds on that it is the vacum as when the engine gets hot /up to temp it is sealing the hose so i would look at that first with the posibility of replacing the vacum hoses and posability of the egr valve as well if it is fitted to your model some did some didnt it depends on where in the world it was assembled

You can check the A/C and power steering belts. They nay be due for tensioning.

So I had the same issue. However, when I accelerated it did not make the sound but when I take my foot off of the gas it does. My sound it deafening though. The issue is the valve has broken. The valve also known as PCV, Crankcase, Oil seperator valve.

It's the pcv valve located under the engine cover. It's actually attached to the engine cover. There is a cheap fix where you can buy just a portion of the part. Trust me. Just buy the whole part.

My daughter's '06 Passat (3.6l 4motion turbo) is doing the same thing. We've replaced the pcv valve though and it's still doing it.

Rebecca. Did you go the cheaper route and buy the partial part? I've read that doesn't work sometimes.

We bought the whole part, the previous owner had used a small piece of hose to repair it at some point.

Rebecca. I'm still convinced it's the PCV. It wouldn't be the first time a new part was broken or defective. Check out this video for testing. https://youtu.be/3uXfqRk6kok