stephenhacker23

I have an 07 CLS 550 W219 and I got into the engineering mode on the head unit last night in order to try and access the hidden menu. I was unsuccessful in getting the hidden menu, however, now when the head unit is powered off, I am getting a slight hiss or feedback sound coming from the car speakers.

Its quite annoying. Does anyone know how to rid of this hiss / feedback sound after powering down the head unit?

Thanks!