As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED LAVATORY SMOKE WARNING MESSAGE ON THE EICAS DURING FLIGHT. NO VISIBLE SMOKE NOTED. MAINTENANCE REPLACED THE LAVATORY SMOKE DETECTOR CONTROL PANEL. PERFORMED ELECTRICAL CHECK IAW FIM 26-14-00-810-802. PERFORMED LAVATORY SMOKE DETECTION SYS CHECK. OPS CHECKED GOOD.