As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE TOILET CAUTION MESSAGE ON DEPARTURE. THE CREW DECLARED AN EMERGENCY, RETURNED TO FIELD, AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED, R & R THE LAVATORY SMOKE DETECTOR AND PERFORMED CHECKS IAW THE AMM. THE ACFT WAS RELEASED FOR SERVICE.