Subwoofer

You may also want to make sure the sub isn't just loose if yours has the 4 plastic pins that hold it. I had my trunk open and was able to push up slightly on the frame. A little outdoor caulking and quieted right down. Though when its cold -40ish the particle/wood the carpet on the rear deck is glued to rattles its weak around the rear of the sub. You can try bracing it somehow I may try some dynomat there to quiet it till can remove back seat for better access.