As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, WHEN LANDING GEAR WAS SELECTED UP, RECEIVED A LANDING GEAR AIR-GROUND FAIL MESSAGE AND LANDING GEAR DID NOT RETRACT. FOLLOWED THE QUICK REF HANDBOOK AND DECLARED AN EMERGENCY. RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. ACFT FOUND SAFE FOR FERRY FLIGHT. MX REPLACED THE NLG WEIGHT ON WHEELS PROXIMITY SWITCH AND NLG PROXIMITY SWITCH HARNESS (W019). OPS CHECKED AND LANDING GEAR SWINGS WERE GOOD WITH NO FURTHER DEFECTS NOTED.