Standard question now here is, do you have an Apple Watch gen 3? That messes up the signal and I've not seen info that a fix is in the works or not from Apple. Put the watch in airplane mode and try it. (It's the LTE on the watch, whether you have it set up or not.)
no apple watch...I saw that thread...Iphone 6 though, wondering if its just too old to work right with the car. Since it doesn't seem to be a general problem, I think I'll make an appointment to get it checked.