As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT GATE, APU SHUTDOWN ABRUPTLY FOR NO REASON. VERIFIED DISCREPANCY. PERFORMED APU BITE. PERFORMED FIM TASK 49-90 TASK 803. APU OIL LEVEL AND MAGNETIC DRAIN PLUG OK. R & R APU LOW OIL PRESSURE SWITCH IAW AMM 49-94-22. GROUND VERIFICATION SUCCESSFUL. APU OPS NORMAL.