As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FAULT LIGHT ILLUMINATED ON APU DURING START. GROUNDED - YES. PERFORMED APU BITE TEST FOUND FAULT 49-31016 OVERTEMP SHUTDOWN. PERFORMED B737-900 FIM 49-30 TASK 803 GVI OF APU INLET DUCT AND COMPRESSOR INLET PLENUM WITH NO DEFECTS NOTED. STARTED APU 4 TIMES, ALL STARTS NORMAL. NO FAILURES FOUND. A/C OK FOR SERVICE.