As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE NR 4 ENGINE NACELLE FIRE DETECTOR A LOOP FAULT WITH P2 PANEL LIGHT ILLUMINATED. FAULT NEEDLE WENT BACK TO NORMAL AFTER 3 HOURS-LIGHTS OUT. RESEATED NR 4 ENG "A" FIRE DET LOOP WARNING AND CONTROL CARDS A4 AND A7. PERFORM SYS OPS CHECK IAW 26-12-01. SYS OPS NORMAL.