As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3707 DURING THE CLIMBOUT THE CREW REPORTED, RECEIVED AN AIR/GROUND FAIL MESSAGE ON EICAS THAT REMAINED ON FOR DURATION OF FLIGHT. THE CREW ELECTED TO RETURN TO ORD. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE LANDING GEAR ELECTRONIC CONTROL UNIT IAW EMB AMM 32-32-01. THE OPERATIONAL CHECK WAS GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.