As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW NOTED THAT THEY HAD INCORRECT FLAP INDICATIONS WHILE CONFIGURING THE AIRCRAFT FOR LANDING. THE FLAPS INDICATED 13 WHEN SET TO 15 DEGREES AND 18 WHEN FLAPS 20 WAS SELECTED. THE CREW DECLARED AN EMERGENCY AND RETURNED TO FIELD. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE PERFORMED OPERATIONAL CHECKS OF THE FLAP SYSTEM WITH NO DEFECTS NOTED.