As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 7820, CMH-IAD, AFTER TAKEOFF AT 400 FEET, THE CREW RECEIVED A LAV SMOKE MESSAGE. THE FLIGHT ATTENDANT REPORTED THAT THERE WAS NO SMOKE PRESENT IN THE LAVATORY OR CABIN. THE FLIGHT RETURNED TO CMH AND LANDED WITHOUT INCIDENT. MAINTENANCE RAN THE ENGINES AND ISOLATED THE FAULT TO E1. WHEN RUNNING ON THE NUMBER 1 ENGINE THE COCKPIT FILLED WITH SMOKE THAT HAD AN OILY SMELL. NO EXTERNAL LEAKS WERE FOUND AND THE ZERO CARBON SEAL WAS DRY. E1 WAS REPLACED AND THERE WAS NO FURTHER SMOKE OR ODOR.