Had my annual today.Late afternoon LA time my PCM repeatedly powered down mid-drive powered back up, Porsche badge, Cayman badge, then returned to tuner. This happened constantly for the entire drive. Ddi not matter if I tuned to FM, same thing occurred, but tuner would return to XM after power down. Spoke to Rusnak dealer here in SoCal, he's been getting calls all morning. It seems a bug in XM satellite software upgrade is responsible, unclear if limited to Porsche, but seems to be effecting slightly older, (mine 2014) PCM's.
I did the following and it reset my CDI and stopped the reboot.
I told me it did not work for everyone.
My XM worked fine.
In your Car;
Press Car button on dash
Choose Option tab
Choose Vehicle Handover
Resets all data - presets, recordings, phone numbers, etc.
To find reference to above
Car Owner’s manual- info
I used Good To Know app
I searched for Car on home screen
I scrolled down to Settings, I chose Car here
Car menu comes up
Scroll down to Advanced Car Menu
Follow Vehicle Handover Instructions