High pitched Hum
 

Sometimes after I turn off my 02 S I can hear a loud high pitched hum coming from somewhere around the drivers side of the dash. It is really weird because everything is turned off yet sometimes the sound is there and will last for maybe ten seconds or so. Any ideas on what it could be?

My guess is the fan that cools the hot engine.

My dual DIN Navigator/Stereo has a little fan in back that runs for a moment after I shut the engine down.

Also the Front radiator cooling fans on occasion.

Does it still make the sound after the key is out of the ignition?

Not your AC/heating fan?

It's not the fan cooling the hot engine as I know what that is but it's an intermittent high pitched sound, almost like a whistle. It just sounds like its coming from somewhere near the dash on the drivers side and it doesn't happen all the time after a drive. It will make the sound even with the key not in the ignition and only lasts for 5 to 10 seconds. It doesn't sound like a fan and it is hard to pinpoint the exact location.

The HVAC system "doors" losing pressure?

Not the Secondary Air Pump? (I know you said dash area, but sound source can be deceiving sometimes)

Thanks for all the diagnosis and input. I am assuming it is not something to worry about, no codes and no performance problems. I will keep an eye on things and post any changes to the situation.