As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAH - FLIGHT 4211, THE CREW REPORTED A LANDING GEAR AIR GROUND FAIL MESSAGE IN CRUISE. THE AIRCRAFT RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED THE LEFT HAND MAIN LANDING GEAR WEIGHT ON WHEELS PROX SWITCH, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.