As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) CLIMBING THROUGH FL20 THE F/E ADVISED OF PRESSURIZATION PROBLEMS. AFTER REDUCING TO 10,000 FT. CABIN INDICATED 10,000 WITH 3 PSI DIFF.WHEN THRUST REDUCED THE DIFF WAS 0. THE AIRCRAFT RETURNED TO POINT OF DEPARTURE. MAINTENANCE REPLACED THE PRESSURIZATION CONTROL PANEL AND THE PRESSURE CONTROL MODULATING SOV. THE SYSTEM WAS FUNCTION CHECKED AND THE AIRCRAFT RETURNED TO SERVICE. (TC NR 020060427004)