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 AFTER TAKEOFF, GEAR WOULD NOT RETRACT." MAINTENANCE REMOVED AND REPLACED THE LEFT TRAILING ARM PROXIMITY SWITCH IAW EMB145 MM NR 32-63-01. OPS CHECKED OF LANDING GEAR AIR/GROUND SYSTEM AND LANDING GEAR SWING GOOD IAW EMB145 MM NR 32-63-03. AIRCRAFT RETURNED TO SERVICE.