As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDIS WRI 26-12-5025 AT ABOUT 1500 AFT MAIN DECK CARGO LOOP-A ILLUMINATED, FOLLOWED BY LOOP-B AND RED SMOKE LIGHT & ECAM FIRE WARNING. DECLARED EMER AND RETURNED TO LAND. REMOVED AND REPLACED AFT UPPER CARGO SMOKE DETECTION CONTROLLER AND TESTED PER MM 26-19-00. RAN BOTH ENGINES AND RAN A/C PACK SYS USING BLEED AIR. NO SMOKE OR ODOR NOTED IN CABIN, PER JRH SMOKE DETECTION SYS SHOWED NO FAULTS.