I had this issue awhile back on my 2007 Coupe. Ended up being water entering thru the threaded holes where the factory dead pedal was mounted. I had removed the factory one and installed a M-B version that matched the bright pedals in the Coupe. What I was never able to understand is why this wasn't an issue for a couple of years after I installed the M-B dead pedal and then suddenly allowed water to enter the floor pan.



Keep telling myself to remove the factory dead pedal, plug the holes for the screws and then re-install the M-B dead pedal. Curious if water comes back