My sync every time I start truck (2015 f150) says 911 assist not working! see your dealer, how do I turn off that message?

 

I got it one or two times after I did an update, here's what I did to fix it. I got out of my truck, locked it, waited about 10 minutes for everything to completely power down then remote started my truck, waited about 5 minutes for sync to fully boot up (probably didn't really need to wait that long) then unlocked my truck, got in and turned the key on. No more 911 messages, guess it just needed to fully go through some power up before it connected via bluetooth to my cell. Not sure why but that worked for me when I first got my truck over a year ago and also last week after I upgraded the software. Good luck.
Tom

 

Is 911 Assist enabled in your Sync3 settings? I think it's set to 'Off" from the factory, and defaults to 'Off' after a master reset as well.