Originally Posted by FriendlySkies

It's possible that an agent printed BP in FRA will not have the proper encoding for PreCheck. You could do online checkin while in Frankfurt, and if you are cleared for PreCheck, it will print out for your SFO-HNL BP. Another option is to use a mobile BP.

If you can't OLCI or use mobile BP, just go to an agent in SFO or use a kiosk.