As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, UNABLE TO CONTROL THE CABIN ALTITUDE. LEAK CHECKED AIR CONDITIONING SYSTEM, NO LEAKS NOTED. PRESSURIZED AIRCRAFT TO 3.0 PSI AND NO LEAKS NOTED. REMOVED AND REPLACED CABIN PRESSURE CONTROLLER PER MM 21310. SYSTEM OPERATIONALLY CHECKS NORMAL.