As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 6399 CMH-BDL - AFTER TAKEOFF, A LAV SMOKE MESSAGE APPEARED ON EICAS. A HAZE WAS SEEN IN THE COCKPIT AND A LIGHT SMOKE COULD BE SEEN IN THE GALLEY. AFTER THE CHECKLISTS FOR LAV SMOKE WERE COMPLIED WITH, THE MESSAGE EXTINGUISHED. THE AIRCRAFT RETURNED TO FIELD AND LANDED UNEVENTFULLY. MAINTENANCE TROUBLESHOT THE SYSTEM AND FOUND THE OIL SMELL AND RESIDUE INSIDE BLEED AIR DUCTS. REMOVED AND REPLACED NR 1 ENGINE WITH NEW AND OPS CHECK AND LEAK CHECK GOOD PER EMB J/C CE720001.