As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT AN AUTO PRESSURIZATION CAS MESSAGE ILLUMINATED. TROUBLESHOOTING OF THE AUTO PRESSURIZATION SYS FOUND THE MAIN OUT FLOW VLV TO BE DEFECTIVE. THE DEFECTIVE OUT FLOW VLV WAS REMOVED & A NEW VLV WAS INSTALLED IAW MM CMP TASK 213008.