As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT DURING AIRCRAFT POWERUP THE NO2 YAW DAMPENER DISPLAYED INOPERATIVE. THE MAINTENANCE VENDOR TROUBLESHOT AND DETERMINED THE AUTO-PILOT CONTROLLER WAS DEFECTIVE AND WAS REPLACED WITH AN OVERHAULED CONTROLLER. OPS CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.