As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOW APU PRESSURE ON START. 8 PSI. HAD TO BOOST APU TO START. SUP: AFTER DE-BRIEF CREW, THEY HAD GOOD PRESSURE UNTIL THEY ATTEMPTED AN ENGINE START IN AUTO. THE PRESSURE SLOWLY DROPPED TO 8 PSI WHEN THEY INITIATED AN APU BOOST TO RECOVER THE LOW PRESSURE. REPLACED THE INLET PRESSURE TEMP SENSOR APS 3200. APU BLEED PRESSURE NORMAL.