As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4883, ON THE GROUND AT GATE CREW GOT THE LAV SMOKE ON EICAS. CREW REPORTED THAT THERE WAS SMOKE AND POSSIBLE FIRE IN LAV. EVACUATED AIRCRAFT BY STAIRS. FIRE DEPT INSPECTED AIRCRAFT AND FOUND NO EVIDENCE OF FIRE. AIRCRAFT REMOVED FROM SERVICE. SMOKE IN CABIN CAUSED BY INTERNAL LEAKING INSIDE APU. REMOVED AND REPLACED APU IAW W/C 49-800-05. NO LEAKS NOTED. NO FURTHER DEFECTS NOTED AT THIS TIME. AIRCRAFT RETURN TO SERVICE.