As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKE-OFF, CREW RECEIVED A LAVATORY SMOKE WARNING. NO VISIBLE SMOKE WAS REPORTED. RETURNED TO DEPARTURE. NO EMERGENCY WAS DECLARED. LANDED WITHOUT INCIDENT AND TAXIED TO GATE UNDER ITS OWN POWER. MAINTENANCE REPLACED LAVATORY D SMOKE DETECTOR IAW AMM 26-17-15, AND AMM 26-17-00.