I have an Alarm type/humming sound (though not too loud) coming from my motor, I do not believe it is a belt as it doesn't sound like any belt noise I have heard before. I have heard this sound twice now when stopped and just letting the car idle (doesn't mean it isn't there when I am driving). If I turn the car off then back on the sound is gone. Anyone have any ideas? Oh yes, I have a stock 2003 1.8t

Thanks

 

does it get louder the higher the rpm? Do you have the radio on or does it sound like its coming from the speakers?

 

maybe it is the diodes in the alt.