As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OF THE FLIGHT FROM IAD TO JFK, THE CREW REPORTED THAT THE CABIN WOULD NOT PRESSURIZE IN MANUAL MODE. THE AUTOMATIC MODE WAS INOPERATIVE AND ON DMI. THE AIRCRAFT RETURNED TO IAD AND LANDED WITHOUT INCIDENT. MAINTENANCE PERSONNEL REMOVED AND REPLACED THE CABIN PRESSURE CONTROLLER. AN OPERATIONAL CHECK WAS SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.