As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A LANDING GEAR AIR/GROUND FAIL MESSAGE AFTER TAKEOFF AND THE GEAR WOULD NOT RETRACT WHEN COMMANDED. THE AIRCRAFT RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT PER FIM 32-63-00 AND FOUND THE NOSE LANDING GEAR WOW PROX SWITCH TO BE AT FAULT. THE PROX SWITCH WAS REPLACED AND THE AIR/GROUND SYSTEM OPS CHECK GOOD.