As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FWD EQUIPMENT VAL EICAS MESSAGE IN FLIGHT, PRESSURIZATION NORMAL. PERFORMED VALVE OPS OPEN AND CLOSED MANUALLY SATISFACTORY. OPS CHECK AUTO MOD SEVERAL TIMES SATISFACTORY. ALSO POWER LINE CHECKED OVERBOARD EXHAUST VALVE TO CONTROL PANEL SATISFACTORY IAW WDM 21-58-13 D280T199, REF AMM 21-58-00-501.