As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX-ON FLIGHT NUMBER 2553, LEFT HAND PACK CAUTION MESSAGE. PACK SELECTED OFF (CHECKLIST), STATUS MESSAGE LEFT PACK OFF VERIFIED. CAUTION MESSAGE OUT. MDC READS "FLOW CONTROL VALVE MPE11, NO CONTROL/POS DISAGREE" IN FAULT HX. COMPLIED WITH FIM. PERFORMED OPERATIONAL TEST NORMAL WITH NO CURRENT FAULTS. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.