I should have updated my last post. After taking the phone to the Apple store and having it check out fine, we went back to the dealer and insisted it was a problem with the car. They had a few employees try synching their personal phones with our car and nothing happened. One of the mechanics went under the seat and unplugged and replugged in a wire on the bluetooth module and that was it, it works fine now. Must just have needed to be reset!
I'm having the same problem. I very recently bought a 2010 certified pre-owned Wolfsburg Edition Jetta. My iPhone 4 running iOS 5.1.1 pairs but does not maintain a connection. The orange link light blinks, the Bluetooth screen on my phone shows "Connected" then "Not Connected" alternating every 5-15 seconds. The phone never stays connected.
My wife has an iPhone 4S running iOS 6.X. Same problem, pairs but has never successfully connected.
My mother also has an iPhone 4S running IOS 6.X. On my first attempt to pair and connect that phone it did so immediately, no problem. I then had the phone forget the device, turned off the car, restarted the car, then re-paired the phone. I was unable to connect that phone again after repeated attempts.
I have rebooted all the phones, and each time I try again I turn off and restart the car. I have tried rebooting the bluetooth unit by the simple process of unplugging and re-plugging its main power harness, but that does not help. The VW dealer had a mechanic with an iPhone 5 that was able to connect, so he has told me the problem is with my phone. I have a hard time understanding that, as 3 iPhones that are appropriately aged with the car can't maintain a connection but a newer phone did. I'd also question whether the mechanic's phone would repeatedly connect, as was the problem with my mother's phone, but that I suppose I'll never find out.
I contacted VW Customer Care and the representative I spoke to began a case with me, agreeing that it would seem the iPhone 4 should be compatible with the bluetooth unit. I mentioned the problems noted in this and other threads and she was seemingly unaware, but agreed that as a certified car this should be rectified. The only problem is, I have no idea what unit would end up being appropriately compatible. If they replace it with another of the same, based on these discussion threads, isn't it a matter of hit-or-miss?
If anyone has replaced their bluetooth car unit with another that works with an iPhone 4, I'd be curious to know what that unit number is. Also, if anyone then upgraded their unit and had problems after upgrading their phone at a later date, I'd be interested to hear that, too.
Of course, any other suggestions how I might be able to get the existing unit to work, I'd certainly prefer to be able to do that.