As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW DESCRIBED THAT THE OXYGEN SYSTEM EMPTIED TO QUICKLY. UPON FURTHER INSPECTION, DETERMINED THAT THE PRESSURE REGULATOR WAS LEAKING UNDER THE CAP / KNOB USED TO TURN THE REGULATOR ON AND OFF. THIS AREA WAS UNABLE TO GAIN ACCESS USING LEAK DETECTION FLUID.