As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - FLT 2484 - AIR TURNBACK, AIRCRAFT DEPARTED DEN AND WOULD NOT PRESSURIZE ON ONE BLEED (NR 2 BLEED ON MEL). AIRCRAFT FERRIED TO PHX. ENGINE NR 1 HIGH STAGE VALVE TEST FAILED. REMOVED AND REPLACED NR 1 HIGH STAGE VALVE. REFERENCE MEL 36-05. FOUND CRACKED PRECOOLER. REMOVED AND REPLACED PRECOOLER AND SENSE LINES. REFERENCE AWXA960299.