As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED A LAV SMOKE WARNING IN FLIGHT WITH NO SMOKE OR FIRE IN THE LAV. ACFT WAS DEICED ON THE GROUND AND PREVIOUS WRITE UP OF LAV SMOKE WAS NOTED. MAINTENANCE INSPECTED AND CLEANED THE SMOKE DETECTOR SCREEN. OPS CHECKS WERE GOOD.