As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE AT FL330, THE MASTER WARNING AND RED CABIN PRESSURE LIGHTS ILLUMINATED AND CABIN PRESSURE INDICATED 1000 FEET. COMPLIED WITH COM PROCEDURES. AIRCRAFT DESCENDED TO 10,000 FEET BUT CREW COULD NOT CONTROL THE CABIN PRESSURE. MASKS DEPLOYED AUTOMATICALLY PRIOR TO DESCENT. FLIGHT LANDED AT DTW WITHOUT INCIDENT. MAINTENANCE REPLACED THE LEFT FLOW CONTROL VALVE. OPERATIONAL CHECK OK.