As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON ENG START APU FAULT LIGHT ILLUM AND AUTO S/D ON PUSH BACK. APU ECU FAULTED LOW OIL PRESS SW PREV REPLACED. REPLACED OIL LUBE PUMP AND ECU APU NOW STARTS AND RUNS. ATTEMPTED ENG ST WAS SUCCESSFUL LEAK CHECK OK A/C RTS WITH FULL SERVICE APU PUMP MFG NR 3880190-10.