As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB CREW RECEIVED A NOSE GEAR DOOR OPEN MESSAGE. CREW RETURNED TO FIELD AND LANDED UNEVENTFULLY, NO EMERGENCY WAS DECLARED. PASSENGERS WERE DEPLANED AT GATE. MAINTENANCE PERSONNEL REMOVED AND REPLACED THE NOSE GEAR SELECTOR DOOR VALVE. A SATISFACTORY FUNCTIONAL CHECK WAS PERFORMED AND AIRCRAFT WAS RELEASED FOR CONTINUED SERVICE.