As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3509 CREW REPORTED YAW DAMPER FAIL AND AUTO PILOT KICKED OFF DURING CLIMB FOLLOWED BY RUDDER SYSTEM 1/2 INOP EICAS MESSAGE. CREW ELECTED TO RETURN TO DFW FOR MAINTENANCE DECLARED EMERGENCY PRIOR TO LANDING. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED RUDDER NR 2 PRESSURE SWITCH IAW EMB 145 AMM 27-23-04. PERFORMED OPERATIONAL CHECK OF THE RUDDER SYSTEM, J2 AMM 27-23-00. OPERATIONAL CHECK GOOD AT THIS TIME. AIRCRAFT RETURNED TO SERVICE.