As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
REPORTED BY CREW DURING FAULT/INOP TEST "APU DET INOP" LT REMAINS ILLUM. APU FIRE TEST FAILS. APU UPPER DETECTOR AND M1756 APU LWR DETECTOR ARE GOOD WITH COMBINED RESISTANCE OF 1.3K OHM. FOUND M1925 APU TAIL PIPE OVHT DETECTOR DEFECTIVE AND OPEN. REPLACED APU TAILCONE DETECTOR WITH SERVICABLE ONE. TEST PASSED IAW MM 26-15-01-400-802.