As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED THAT THE CABIN ALTITUDE INDICATION WAS LOST ON CLIMB OUT WHILE THE AUTO PRESSURIZATION SYSTEM WAS DEFERRED. THE AIRCRAFT RETURNED TO FIELD AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE VERIFIED THE ELECTROPNUEMATIC VALVE WAS PROPERLY DEACTIVATED. OPERATIONAL CHECKS OF THE CABIN ALTITUDE INDICATION SYSTEM WERE GOOD WITH NO FURTHER DEFECTS NOTED.