As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT DURING CLIMB, THEY RECEIVED A LAVATORY SMOKE INDICATION ON THE EICAS. A LIGHT SMOKE WAS PRESENT IN THE CABIN. DECLARED AN EMERGENCY & RETURNED TO FIELD. THE CREW REPORTED THAT THE ODOR PRESENT SMELLED LIKE DE-ICING FLUID & THAT THE ACFT HAD BEEN DE-ICED PRIOR TO TAKEOFF. THE ACFT LANDED WITHOUT FURTHER INCIDENT. PERFORMED ENG RUNS & OPERATIONS CHECKED THE PACK SYSTEM. NO DEFECTS WERE NOTED & THE ACFT WAS RETURNED TO SERVICE.