As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED, RECEIVED A LANDING GEAR AIR/GROUND FAIL MESSAGE IN FLIGHT. RETURNED TO KCAE AND LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS FERRIED TO KCMH WITH THE LANDING GEAR DOWN AND THE LOCKING PINS INSTALLED. CMH MAINTENANCE ADJUSTED THE RIGHT FORWARD PROXIMITY SWITCH TARGET GAP AND REPLACED THE LEFT FORWARD MAIN LANDING GEAR WEIGHT ON WHEELS HARNESS. OPERATIONAL CHECKS WERE GOOD WITH NO FURTHER DEFECTS NOTED.