As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AUTO SHUT DOWN RESTARTED AND AUTO SHUT DOWN SECOND TIME. APU ECU FAULTED GEN FILTER. ACCOMPLISHED FIM REF MM SHEET 1. BLOCK 1 CHECKED GOOD. BLOCK 2 HAD HIGH RESISTANCE 1.6 OHM'S. REPLACED APU GENERATOR DELTA P SWITCH PER MM. APU OPS CKS GOOD. NO ECU FAULTS.