As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3159 DISC: DURING CAPT OXYGEN MASK TEST THE MASK STARTED FLOWING OXYGEN NON - STOP. THE MASK WAS REMOVED. SPINNING THE EMER DIAL AND FLIPPING THE 100% SWITCH HAD NO EFFECT. AFTER ABOUT 45 SECONDS IT SHUT OFF WITH NO OTHER ACTIONS. C/A: R&R CAPT'S O2 MASK IAW A319 AMM 35-12. OPS & LEAK CK. GOOD. A/C OK FOR SVC. (LP: 860810). AIRCRAFT WAS GROUNDED