As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) CREW REPORTED THAT DURING CLIMB AT ABOUT 14,000 FT AN AURAL WARNING WAS HEARD FOLLOWED BY DEPLOYMENT OF PASS O2 MASKS. EMEG DESCENT AND RETURN TO BASE. MAINT INSP CARRIED OUT AND NO DISCREPANCIES FPUND, ONGOING INVESTIGATION. PRESSURE CONTROLLER REPLACED.