2006 Subaru Impreza 2.5 - radio whining/buzzing noise

A few months ago, my car started making a loud whining/buzzing sound when I started it. The sound is distinctly coming through the speakers in the car, but turning the radio volume knob doesn’t make it quieter or louder (though turning the radio completely off makes the sound stop). The sound persists until the car warms up, then the buzzing sound slowly fades away, and the voice/song on the radio slowly comes back until the buzzing sound is completely gone.

I recently took my car to a mechanic to have the timing belt and head gasket replaced, and the mechanic couldn’t figure out what the problem was. Does anyone have any ideas as to what could be the root of this problem?

Could be a loose ground of sorts. You could take the part of the dash that holds the radio in off and see if making a temporary connection between the case of the radio and a good ground makes a difference. A booster cable (just the negative side) is a good way to make a good ground connection.
If it doesn’t go away, it could be your radio, your charging circuit, etc.

What you might do is remove the serpentine belt or the belt that drives the alternator; start the Subaru; and see if the whine/buzz is still there. You should not have to run the engine long to find out if the problem is with the charging system.

I am thinking that there may be a problem with the alternator (either brushes or rectifier). It also could be a high resistance path from the alternator to the battery.

Hope this helps.

From what you say about the trouble it sounds like the trouble is inside the radio. If the noise is so great that it overrides the normal audio I think you are going to have to replace the radio. There is a possibility that the alternator is causing the noise and a simple way to see if that is the case is to remove the connector at back side of the alternator, then start the engine and see if the noise is gone. If the noise is still there then the radio would be the problem. I assume there isn’t an external amp tied to the radio but if there is then I would suspect the amp is causing the trouble rather than the head unit.

Does the pitch of the whine increase with engine RPM’s? If so, my guess is a bad diode in the alternator causing a high “ripple voltage” in the output. It could get into the audio power amplifier in the radio which is after the volume control.

Reviving this thread from last year. I had this issue since last year and my mechanic was able to fix it this year. It is/was a grounding issue. The symptoms were exactly like yours and running some additional thick grounding cables to the neg terminal on the battery and the motor and body fixed it. I can post a picture if someone needs it.

BTW the pitch of the whine did not increase with RPM’s.

Good luck.

Thanks for the feedback @Boomcha. That info may help some other folks. I think there is a main ground point at the back and middle of the engine that some of the dash systems tie to also along with the battery to chassis connection. Cleaning all the ground connections under the hood is a very good thing to do. I know there are a number of folks that have added extra grounding wires also to help clean up some issues.

My 2007 Impreza has the radio buzz too, and has since i bought the car… It took me awhile to realize that it coincides with the headlights being turned on (not including the daytime running lights). I can drown out the buzz by increasing radio volume, so I stopped worrying and now just ignore it.