As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. EMERGENCY DECLARED. MIA-BCN FLIGHT RETURNED TO MIA ACCOUNT CREW OXYGEN PRESSURE DROPPED TO ZERO DURING CRUISE. OVERWEIGHT LANDING UNEVENTFUL. REMOVED AND REPLACED CREW OXYGEN PRESSURE TRANSDUCER IAW AMM 35-11-03. OPERATIONAL CHECK GOOD.