As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SDF TO IAH - DURING APPROACH INTO IAH, CREW RECEIVED "APU OVERTEMP" AURAL WARNING AND MESSAGE AFTER SWITCHING BLEEDS TO APU. CREW OBSERVED THE TEMPERATURE REACHED 999 DEGREES CELSIUS. COMPLETED THE QRH FOR APU OVERTEMP MSG. EGT WAS SUSTAINED AT 999 DEGREES AND CREW DECLARED AN EMERGENCY. MAINTENANCE INSPECTED APU AND FOUND THE APU OIL OVERSERVICED. MAINTENANCE SERVICED OIL TO THE PROPER LEVEL AND OPS CHECKED THE APU. APU OPERATED NORMALLY AFTER SERVICING.