As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRES DURING FLIGHT AT 12000 MSL THE CABIN ALTITUDE WARNING LIGHT AND ALTITUDE HORN ACTIVATED. CREW CONTACTED ATC AND REQUESTED AN IMMEDIATE AND RAPID DECENT TO 9000 FEET HORN AND LIGHT WENT OUT. FLIGHT CONTINUED TO DESTINATION. MAINTENANCE PERFORMED A SINGLE PACK OPERATION CONFIDENCE CHECK PER B737 AMM 21-00-05. THE FLOW CONTROL VALVE WAS ALSO CHANGED AS A FURTHER PRECAUTION.