As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A PASSENGER DOOR MASTER WARNING WITH ASSOCIATED AURAL WARNING AT 600 FEET AGL AFTER TAKEOFF FROM TLH. AIRCRAFT RETURNED TO TLH AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT THE AIRCRAFT, REMOVED AND REPLACED A PASSENGER DOOR PROXIMITY SWITCH AND ASSOCIATED SPLICES AND PERFORMED CHECKS USING THE AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT WAS RELEASED FOR SERVICE.