As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: LAVATORY 3L SMOKE DETECTOR CAME ON AND ALERTED COCKPIT IN FLIGHT FOR 3 MINUTES, THEN WENT OFF. NO SMOKE FOUND IN LAVATORY 3L. ACCOMPLISHED SATISFACTORY CHECK OF SMOKE DETECTOR PER AMM 26-12-00. NO FAULTS NOTED.