As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO MAINTAIN CABIN PRESSURE IN AUTO AND MANUAL MODE. WHILE IN CRUISE AT 28,000 CABIN PRESSURIZATION RAN AWAY 2000 FPM UNCONTROLLABLY. CLOSED CARGO OUTFLOW VALVE AND PRESSURIZATION OUTFLOW VALVE. CABIN STILL CLIMBING DURING DESCENT AND PRESSURIZATION RECOVERED. DIVERTED TO PHX. *S/D* FOUND THE CABIN PRESSURE RELIEF VALVE STUCK OPEN. REPLACED VALVE.