As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - CREW RETURNED TO FIELD WHEN AFTER TAKEOFF THE RIGHT GEAR DOOR AND GEAR UPLOCK LIGHTS ILLUMINATED FOR APPROXIMATELY 2 TO 3 MINUTES. GEAR EXTENSION WAS NORMAL. MAINTENANCE INSPECTED THE AIRCRAFT AND FOUND THE MAIN GEAR UPLOCK PROXIMITY SENSOR IN THE FAR CONDITION. MAINTENANCE ADJUSTED THE MAIN LANDING GEAR UPLOCK PROXIMITY SENSOR ON THE RIGHT GEAR IAW WITH THE MAINTENANCE MANUNAL. OPERATIONAL CHECKS WERE PERFORMED AND CHECKED GOOD. AIRCRAFT WAS RETURNED TO SERVICE.