As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE OPERATING THE APU IN FLIGHT WITH THE NR 2 GENERATOR PLACARDED INOPERATIVE, THE APU SHUTDOWN. THE APU WOULD NOT RESTART. THE AIRCRAFT LANDED AT IAH WITHOUT INCIDENT. MAINTENANCE FOUND THE APU FUEL CONTROL UNIT AT FAULT. THE APU FUEL CONTROL UNIT WAS REMOVED AND REPLACED IAW MM 49-30-01, OPERATIONAL CHECKS WERE GOOD.