As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE FLIGHT, THE CREW REPORTED RECEIVING A LANDING GEAR AIR/GROUND FAIL MESSAGE ON THE EICAS. MAINTENANCE REMOVED AND REPLACED THE LT MLG AFT PROXIMITY SWITCH AND RELAYS K0353 & K0453 IAW AMM PROCEDURES. FOLLOW ON OPERATIONAL CHECK OF THE LANDING GEAR EXTENSION AND RETRACTION SYSTEM WAS GOOD.