As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4455 AFTER TAKEOFF THE CREW REPORTED, RECEIVED A LANDING GEAR AIR/GROUND FAIL MESSAGE AND A WEIGHT ON WHEEL INOPERABLE MESSAGE ON EICAS. THE CREW ELECTED TO RETURN TO JFK. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE LEFT ARM PROXIMITY SWITCH IAW EMB AMM 32-63-01. REMOVED AND REPLACED DOWNLOCK PROXIMITY SWITCH HARNESS AS PER AMM 20-50-00. RETRACTION AND EXTENSION CHECK FOUND TO BE WORKING. THE AIRCRAFT WAS RETURNED TO SERVICE.