As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OUT FROM PNS, THE CREW RECEIVED A NOSE GEAR DOOR OPEN WARNING. THEY RAN THE QRH, WHICH INSTRUCTED THEM TO LAND AT THE NEAREST SUITABLE AIRPORT. THEY CHOSE TO RETURN TO PNS. NO EMERGENCY WAS DECLARED. REMOVED AND REPLACED PROXIMITY SENSOR PX31, IAW CRJ-900 AMM 32-61-05-000/400-813. OPERATIONS CHECK GOOD.