As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4521 CREW REPORTED ON TAKEOFF CABIN AND COCKPIT FUMES WITH LAV SMOKE INDICATION ON EICAS. ACFT RETURNED TO DEPARTURE FOR AN UNDERWEIGHT LANDING. NO FIRE NOTED. WARNING EXTINGUISHED AFTER LEVEL OFF AT 4000 FEET. ACFT REMOVED FROM SERVICE. REMOVED AND REPLACED LT ENGINE. ACFT RETURNED TO SERVICE.