As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE LANDING GEAR WOULD NOT RETRACT AFTER TAKEOFF FROM IAH. THE OVERRIDE TRIGGER WAS USED PER QRH. THE AIRCRAFT WAS RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE AIR SAFETY SENSOR OUT OF RIG. THE SENSOR WAS ADJUSTED IAW MM 32-09-01. THE GEAR WAS SWUNG AND OPERATION CHECKED GOOD.