As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - SMOKE COMMING FROM APU EXHAUST AND ALSO BEING CIRCULATED THROUGH AIR CONDITIONING PACK NR 2. FUEL FOUND IN APU OIL SYSTEM. APU OIL TANK REPLACED AND APU RESERVICED WITH OIL. APU OPS CHECKED AND NO SMOKE OR SMELL NOTED FROM NR 2 PACK. AIRCRAFT RETURNED TO SERVICE.