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 SMOKE WARNING IN FLIGHT LASTED FOR 5 SECONDS. .ONLY LAVATORY THAT WAS OCCUPIED WAS L1, NO EVIDENCE OF SMOKE IN ANY LAVATORY REPORTED BY FLIGHT ATTENDANTS. MAINTENANCE PERFORMED LAVATORY SMOKE DETECTOR TEST FOR L1 ALL CHECKS OK NO FAULTS NOTED PER TSM 26-17-00