As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT 33000 FT WARNING HORN SOUNDED AND COCKPIT LOST PRESURIZATION. CABIN ALT CLIMBED TO 12500 AND AUTO FAIL LIGHT ILLUMINATED ON CABIN PRESSURIZATION CONTROLLER. RAN PRESSURIZATION CONTROLLER CHECK, PRESSURIZED ACFT CHECKED ENGINE PNEUMATICS ALL CHECKED GOOD. WHILE CHECKING PACK SYSTEM FOUND LT PACK CONTROL VALVE WILL NOT SHUT OFF. REPLACED VALVE SYSTEM CHECKS GOOD.