As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED LAV SMOKE WARNING AFTER TAKEOFF WITH NO SMOKE. ACFT PERFORMED UNEVENTFUL AIR RETURN. MX RAN ENGINES AND APU NOTICING ODOR DURING PACK 2 OPERATION. MX REMOVED AND REPLACED THE NR 2 ENGINE, OPS CHECKED GOOD. ACFT WAS APPROVED FOR RETURN TO SERVICE.