Q: cannot hear sound in bluetooth connection

have upgraded iPhone 6 to latest update,and now after deleting and re pairing phone to car bluetooth, cannot hear sound from car system .  Phone always worked before update on same bluetooth system.  I have paired phone with bluetooth system in another car, and it works fine

The phone rings, is answered, but cannot hear sound .   the person receiving call can hear me -, but I cannot hear them

Thanks for any help