As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 7581 CMH TO ORD CREW STARTED THE APU WHILE ARRIVING AT GATE THE AIRCRAFT PARKED FORWARD ENTRY DOOR CLOSED THE FORWARD LAV SMOKE SOUNDED. A FAIRLY STRONG ODOR WAS SENSED JUST AFTER STARTING THE APU. THE CREW INSPECTION IN THE FORWARD LAV DID NOT REVEAL ANY PRESENCE OF SMOKE. MX WAS NOTIFIED. IT APPEARS THAT THE FALSE INDICATION CAME FROM AN OVER SERVICED APU. NO FURTHER MAINT REQUIRED.