As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO THE FIELD IN BOS DUE TO A PRESSURIZATION PROBLEM. CABIN ALT AUTO 1-2 FAILED. CREW VERBAL, MANUAL FAILED AT 22000FT AT DECENT MANUAL MODE STARTED TO WORK. CHECKED BOTH PACK FLOW CONTROL VALVES FOR DAMAGED THROAT PRESSURE SENSING PROBES. CHECKED OUTFLOW VALVE LINKAGE FOR SMOOTH OPERATION & NO DAMAGE. REPLACED CABIN PRESSURE OUTFLOW VALVE ACTUATOR. SYSTEM OP CHECKED OK FOR SERVICE.