As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OUT, THE CREW RECEIVED A GEAR DISAGREE MESSAGE. THE CREW COMPLIED WITH THE QRH AND DECLARED AN EMERGENCY. THE AIRCRAFT RETURNED TO DEPARTURE, WHERE IT LANDED SAFELY. MAINTENANCE REMOVED AND REPLACED THE NOSE LANDING GEAR SELECTOR VALVE ASSY. OPERATIONAL CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (K)