As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD FLT 5926 THE CREW REPORTED THE AIRCRAFT STOPPED DEPRESSURIZING AT ABOUT 4000 FT ON DESCENT. MAINTENANCE INSPECTED AND RELEASED AIRCRAFT IAW MEL PROCEDURES. MAINTENANCE REPLACED THE DIGITAL PRESSURIZATION CONTROLLER. OPERATIONAL CHECKS WERE GOOD.