As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF THE LAVATORY SMOKE MESSAGE APPEARED ON THE FLIGHT DISPLAY'S. CREW ABORTED TAKEOFF AND RETURNED TO GATE FLIGHT LANDED UNEVENTFULLY. FOUND TO BE A FAULTY SMOKE DETECTOR AND IT WAS REPLACED. A SATISFACTORY OPERATIONAL CHECK OF THE LAVATORY SMOKE DETECTOR AND AIRCRAFT WAS RELEASED FOR CONTINUED SERVICE.