As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAILED START AT FL 370, 370, 380 WITH FAULT LIGHT. FAULT EXTINGUISHED IMMEDIATELY AFTER FIRST ATTEMPT AND SWITCHED OFF. FAULT LIGHT EXTINGUISHED AFTER 5 MINUTES AFTER 2ND AND 3RD ATTEMPTS. EGT REACHED 950 EACH ATTEMPT. GROUNDED - YES. REPLACED APU LUBE MODULE REF B737-900 AMM 49-91-11. APU RAN ON FIRST ATTEMPT WITH NO LEAKS NOTED. APU BITE TEST SHOWS NO CURRENT FAULTS.