What is wrong if one car speaker buzzes?

Answer by  SteveO82 (109)

The buzzing speaker may just be loose, but more likely it has been blown out by having the stereo too loud.

Answer by  kelabrown (14)

If one of your car's stereo speakers starts to buzz, the broken component could be the cable that connects your speaker to the amplifier and stereo. This (and not the stereo itself) is most likely the issue if only one speaker exhibits problems. To be sure, you could disconnect the cable from the stereo and see if the buzzing continues.