As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE FROM CLT TO BUF, 100 MILES SOUTH OF PIT, AIRCRAFT LOST AUTO AND STANDBY PRESSURIZATION MODES. HOWEVER, CREW WAS ABLE TO REGAIN CONTROL IN MANUAL PRESSURIZATION MODE AT FL230. DUE TO OPERATIONAL CONCERNS, FLIGHT DIVERTED TO PIT AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE AFT OUTFLOW VALVE PER MM 21-31-11-4. ALSO, REPLACED THE CABIN PRESSURE CONTROLLER. LEAK AND OPERATIONAL CHECK GOOD. ACCOMPLISHED SUCCESSFUL PRESSURIZATION CONFIDENCE CHECK PER JOB CARD J321-00-01.