As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW INFLIGHT T2368/07JUL - DURING CLIMB CREW REPORTED APU FIRE WARNING INDICATION. BOTH FIRE BOTTLES WERE DISCHARGED AND AIRCRAFT RETURNED TO DFW AND LANDED WITHOUT INCIDENT. INSPECTION FOUND NO FIRE. WARNING WAS STILL ON FOR LOOP NUMBER ONE. REPLACED LEFT FIRE LOOP. SYSTEM GROUND CHECKED NORMAL OPERATION.