I mentioned this a while back deep in another thread, and thought it might bear repeating. Here's how I solved my problem with the fingerprint sensor: When I had trouble with the fp sensor (maybe because I get dry hands in the winter), instead of overwriting my old thumbprint, I added my thumbprint as though it were another finger. Each time it stopped working, I would "add another finger" to the list (all of them my right thumb). I have 3 or 4 prints of the same thumb now, and the sensor is near 100% for me. I saw in another thread that when you're looking at your list of fingerprints in the touch id settings and press a finger to the sensor, if there's a match in the list it'll be highlighted momentarily. When I do this with my multiple thumbprints, any one of them might light up depending on how I make contact, but one of them always does. Sorry if this has been mentioned before -- I solved my problem early on, so I haven't read through all the fp sensor threads.