As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT, CABIN PRESSURIZATION SYSTEM DID NOT SCHEDULED ALTITUDE OF DIFFERENTIAL PRESSURE. AN UNSCHEDULED/PRECAUTIONARY LANDING WAS MADE. TROUBLESHOOTING INDICATED FAULTY PRESSURIZATION FLOW CONTROL VALVE. VALVE WAS REPLACED WITH OVERHAULED UNIT. GROUND CHECKS AND SUBSEQUENT FLIGHT CHECK WERE SATISFACTORY.