As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THE 14TH STAGE VALVE CHECK FAIL. THE MAINTENANCE TEAM TROUBLESHOT AND FOUND THE 14TH STAGE ISOLATION VALVE WAS DEFECTIVE. THE DEFECTIVE VALVE WAS REMOVED AND OVERHAULED VALVE WAS INSTALLED. OPERATIONAL CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.