As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5315, MSP TO STL - AFTER TAKEOFF THE FLIGHT CREW RECEIVED A LANDING GEAR AIR/GROUND FAIL EICAS MESSAGE AND THE LANDING GEAR WOULD NOT RETRACT. THE QRH WAS FOLLOWED AND THE AIRCRAFT LANDED WITHOUT INCIDENT BACK AT MSP. THE MESSAGE DISAPPEARED AFTER LANDING. MAINTENANCE PERFORMED A WOW TEST PER THE EMB AMM 32-63-00 AND THE SYSTEM OPS CHECKED GOOD. THE AIRCRAFT THEN CONTINUED ON TO STL WHERE THE FAULT WAS TROUBLESHOT FURTHER. STL MAINTENANCE FOUND THE NOSE LANDING GEAR WOW PROX SWITCH TO BE AT FAULT. THE PROX SWITCH WAS THEN REPLACED.