As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3621 IMMEDIATELY AFTER TAKEOFF CREW REPORTED LANDING GEAR AIR GROUND FAIL CAUTION MESSAGE APPEARED ON EICAS. DECLARED EMERGENCY & IMMEDIATELY RETURNED TO THE AIRPORT & LANDED WITHOUT INCIDENT. THE ACFT WAS REMOVED FROM SERVICE. R & R THE NLG AIR GROUND WOW PROXIMITY SWITCH IAW NRWC 635-ORD-01605 IAW EMB AMM 32-63-02. THE ACFT RETURN TO SERVICE.