2000 Boxster whine/whistle

[John from PA]

My 2000 Boxster 5-speed suddenly started making a whine or whistle.  It seems to be dominant from the drivers side of the vehicle but I'm not 100% certain of that.  My drive was with drivers side window down and every time a car passed in the other direction the noise significantly increased.   It goes away with light throttle.  With foot off the throttle that is when it is most noticeable.  It is a constant pitch regardless of engine speed.  Maybe, and I emphasize maybe, I have had a quick flash of a dashboard light, perhaps brake fluid or ABS, but just a fraction of a second and I was unable to identity positively which light flashed.

 

Thoughts?

Edited November 8, 2020 by John from PA

[ttocs]

I had a high pitched hum / or low pitched whine, depends on how these are defined, and it turned out to be the gas cap. Now this is on the passenger side, but just tossing that out there. Try loosening the gas cap and see if anything changes.

 

Otherwise, I'd suspect a vacuum connection somewhere.

[John from PA]

An FYI, it turned out that the air/oil separator needed to be replaced.  The key thing to look for, when the whistle is occurring, you are unable to remove the oil fill cap due to high vacuum.

 

Total price at an independent was slightly over $500.