As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AUTO SHUT DOWN, CAUSING GATE RETURN. TROUBLE SHOT IAW FIM 49-1 1-00, FOUND REVERSE FLOW ON BITE. R & R INLET TEMPERATURE SENSOR IAW AMM. R & R FLOW SENSING MODULE IAW AMM. ALL OPERATIONS & LEAKS CHECK GOOD AT THIS TIME. APU OK TO CONTINUE.