As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2513 - MHT - FLIGHT CREW REPORTED LAV FIRE WARNING ON CLIMB - SMOKE IN THE LAV - CREW PERFORMED AIR RETURN AND LANDED SAFELY - NO EMERGENCY DECLARED. CONTRACTED MX INSPECTED LAV - NO DEFECTS FOUND - AND PERFORMED ENGINE FULL POWER RUN, APU AND PACKS CHECKS AS WELL. IT COULD NOT DUPLICATE PROBLEM. ACFT WAS APPROVED TO RETURN TO SERVICE.