As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6780 - IAD-DTW - DURING CRUISE, AIRCRAFT MADE AN UNSCHEDULED LANDING DUE TO RT DUCT FAIL MESSAGE ILLUMINATED. MAINTENANCE INSPECTED AND REMOVED AND REPLACED TEMPERATURE SENSOR, OPS CHECK OK. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (M)