Here's a DIY for that fix, I have the same issue but don't have time to DIY yet
Originally Posted by JLJL
anyone know if there is a tsb for the cracking of the back panel where the speakers are located. the panel that is in between the back windshield and seats for the e90. when going over road bumps, i hear cracking noises coming from the back. i believe the back piece is loose. any info would be helpful. thanks.