High-pitched sound from throttle body

[MarkInOhio]

I hope someone here has experience with this issue and can help me solve it. I've done a lot of searching trying find info about this problem (assuming it even is a problem) and found nothing conclusive. I will admit my search skills probably hover around the 65th percentile...

 

My 2000 Boxster S (low mileage, pristine condition) has a fairly quiet but very audible (even to my abused ears) high-pitched sound coming from the throttle body. This occurs with the ignition on but the engine not started. Perhaps it continues with the engine running, but since it is so quiet there is no way to tell. It is constant with the ignition on, warm or cold. Aside from this weird sound, the car runs great.

 

Does anyone know what causes this? Is it a problem? How do I stop it? I can't believe it's normal...

 

And based on the searching I've done, I should probably mention that I am 100% certain that the sound is coming from the electronic portion of the throttle body. It is NOT the secondary air pump.

 

Thanks in advance for any help or advice,

Mark

 

[flyingpenguin]

2000 cars are e-gas IIRC.

 

The noise is normal. It is the tac motor holding the plate in position. It goes away when running because the throttle plate is always moving very very slightly to keep idle speed. Some cars are louder than others. The noise you are hearing is the h-bridge circuit switching back and forth very fast to keep the plate in place.

[MarkInOhio]

So it is normal! Never would've guessed that.

 

Thank you very much for the response!