As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER DEPARTURE, RECEIVED CABIN PRESSURE REGULATOR FAULT FOLLOWED BY CABIN PRESSURE EXCESSIVE MESSAGE. CREW DECLARED AN EMERGENCY AND RETURNED. FOUND NR 1 AND NR 2 CABIN PRESSURE CONTROLLERS 105 HM AND 106 HM FAILING TEST OK AND BITE TEST IAW AMM 21-31-00-501. R & R 1 AND NR 2 PRESSURE CONTROLLERS IAW MM 21-31-11-401 TESTS OF SYSTEMS OK, EFF SOURCE REF IPC 21-31-08-03A-010.