What casuse this intermitent buzzing noise when I cut off my 00 coupe? It sounds like about every 90 seconds it does it for who knows how long. It seems to be coming from under the drivers left rear side. I see a black box, what is it? Thanks David

 

EGR (Exhaust Gas Recirculation)system maybe?
I don't have any experience with that, but that's what it sounds like to me.