As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAH FLIGHT NR 2249 THE CREW REPORTED A LAV SMOKE WARNING IN FLIGHT. THE CABIN FILLED WITH SMOKE MINUTES AFTER TAKEOFF. THE ACFT RETURNED TO IAH AND LANDED WITHOUT INCIDENT. MX REPLACED THE NR 2 ENGINE AND OPS CHECKS WERE GOOD. THE TEARDOWN REPORT REVEALED THE CAUSE OF SMOKE WAS LEAKAGE FROM THE COOL FRONT SUMP.