As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS SIGNIFICANT SYS - DURING REQUIRED INFLT APU START RECEIVED EICAS MESSAGE "APU FAULT" AND OVERHEAD PANEL APU "FAULT" LIGHT. SECOND START ATTEMPT YIELDED SAME RESULT. FL 380, SAT -50 DEGREE, TAT -20 DEGREE, START TIME WAS LESS THAN 1 MINUTE, MAX EGT WAS 815 DEGREE. FOUND PNEUMATIC SENSE LINE DISCONNECTED AT GEAR BOX PRESS REG RECONNECTED SENSE LINE OPS CHECKED GOOD. RAN APU W/NO FAULT NOTED. PRECAUTIONARY REMOVED AND REPLACED APU ECU IAW AMM 49-61-05.