bewell

2014 991 4S with Bose. Started the car this morning and no sound from the system. I tried turning the car off and on, muting and unmuting, changing inputs, and resetting to factory settings. Everything worked fine 3 or 4 days ago when I last drove the car. Nothing worked. Anyone else have this problem?

mangu

If you have any cables connected: try disconnecting any cables plugged into the USB port in the armrest console (or disconnect from all USB ports in the car, just in case)

This is only thing I ever have had happen to my vehicle, once in a blue moon. For me, it appeared the PCM was picking up the cable connection as a connected audio device/source, even when no device was plugged into the other end of the cable.

Hope your issue is as simple as that.

Good luck!

K996

I had this happen after driving through some water up to the floorboards of the car (but not above the bottom doorsill). The PCM display was working but no audio was coming out, ultimately determined that the bose amp (under passenger seat) had gotten wet and shorted out.
In my situation all I could figure out was that the bottom tub of the car isnt 100% waterproof and the water just barely settled into the area under the seat.

PVKPorsche

My 2013 991 Cab had it happen from time to time, very random. I could go for weeks with no problem and then in one week a few times. I tried restarting the car, resetting the PCM, everything and nothing would work but to drive the car, stop, leave it for a while and come back to it working again. The problem was by the time I got to a dealer, it was gone and they couldnt replicate and no codes. Just a real annoyance. Unfortunately no help for you to say what it was but a replacement of the PCM head unit, maybe. Thats what I wanted the dealer to do since my car was CPO but unless they could replicate it, they couldnt replace.