This may have already been posted but heres what worked for me. I just copied what I had said in another thread.
Hello everyone,
I've searched everywhere for tips and tricks on how to fix the issue that a good chunk of us seem to being having in regards to the iPhone 6 not pairing with vehicles. I was frustrated for months trying to figure this out. Did every update possible, thought about going to Apple themselves (but then read that they are no help). I even brought my car to the dealership thinking it was something faulty with my car. Nope. Btw, I drive a 2010 Mazda 3. This is my 3rd Mazda that I have owned and never did I have issues beforehand. I also know people with the exact same car who didn't have issues and friends with different cars who were having issues. Anyways long story short today I finally got it fixed!!!!
I spoke with my cousin who is very techno savvy. I explained to him that whenever it came to the pairing option through the set up in my car, I would get booted. The cars bluetooth would drop me and go right back to the radio. I also explained that when I clicked on my Mazda under bluetooth in my phone, that it could not find my car.
So, I was informed to delete everything under "bluetooth". If there are multiple vehicles, delete them all. Sadly, you'll have to reconnect them (although it seems as though if you have an issue with one car, you'll have it with another). Once done this, I went into the setup menu and went through the process of deleting ALL devices that were paired to my car. I did this and then tried to set it up for pairing. Again my bluetooth dropped me. As you can imagine I was frustrated thinking it wasn't going to work as I had just been dropped for the millionth time.
I tried to pair it right away and was getting no where.
I decided to just turn my phone off and then turn my car off. I waited for my phone to completely reboot then started my car. I went into the setup menu and went through the whole process of setting it up. It paired up perfectly as if there were no issues to begin with. I listened to music and phoned a few people just to make sure there were no issues. After months I finally have my bluetooth back!! yay!
Hopefully this helps some people. I assume it won't help everyone but, I wanted to let you all know what worked for me.