As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS SIGNIFICANT SYSTEM, STATUS MESSAGE "APU OIL QTY" ON TAXI IN. APU RUNNING WHEN SHUT DOWN, MSG WENT AWAY. OIL QUANTITY LOW. RESERVICED OIL OPS CHECK GOOD NO LEAKS NOTED PER REF 49-11-00 FIG 116. FOUND OIL CAP RING WORN AND COCKED AND NOT SECURED PROPERLY, RE-SECURED AND REPLACED SEAL.