As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED, LANDING GEAR AIR/GROUND FAIL MESSAGE ON EICAS ON TAKEOFF FROM NEWARK. AIRCRAFT AIR RETURNED TO EWR, LANDED UNEVENTFULLY. MAINTENANCE REMOVED AND REPLACED LEFT HAND MAIN LANDING GEAR PROXIMITY SWITCH IAW EMB145 MM 32-63-01. OPS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.