As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO LAS DUE TO THE FLIGHT CREW REPORTING THAT THE AIRCRAFT WOULD NOT PRESSURIZE ALONG WITH VENT SKIN VALVE FAULT ECAM MESSAGE. THE AIRCRAFT LANDED SAFELY AT LAX WITHOUT FURTHER INCIDENT. MAINTNANCE REPLACED THE SKIN AIR VALVE AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 21-26-55.