2014 CLS550 Voltage Display on Instrument Panel
Maybe there is an option in that mode? I'm not sure. But what I hear is its a page for bunch of settings that you can change. Some people reported their bluetooth quality was bad and they changed setting in there and it was a lot better.
Check this thread on how to enter/exit the Engineering Mode. And read the thread, maybe you'll find some useful info there.
https://mbworld.org/forums/e-class-w...ring-mode.html


