As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: MID LAVATORY FIRE WARNING WENT OFF IN AIR: NO WARNING IN FLIGHT DECK. MAINTENANCE FOUND ALL LAVATORY SMOKE DETECTORS FILTER SUPER DIRTY, CLEANED ALL LAVATORY SMOKE DETECTOR FILTERS AND ACCOMPLISHED A SATISACTORY OPERATIONAL CHECK PER AMM 26-17-00.