As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU BLEED AIR INOP. CDU BITE PRODUCED FAULT CODE 49 52270 DELTA PRESSURE SENSOR SHOWS OUT OF RANGE DRIFT. REPLACED THE DELTA PRESSURE SENSOR OPS CHECK GOOD NO ACTIVE FAULTS. REF MM 49 52 33. VISUAL INSPECTION COMPLETED OF CONNECTOR AND WIRE HARNESS NO FAULTS FOUND OK FOR SERVICE.