As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT RIGHT DUCT OVERTEMP CAUTION LIGHT CAME ON CLOSING RT BLEED VALVE. AIR RETURN TO DTW. PERFORMED QRH, TRIED RESETTING IN BOTH AUTO AND MANUAL MODE BUT OVER TEMP CONTINUED. MAINTENANCE RE-DEFERRED AUTO PER MEL 21-60-2. MAINTENANCE REPLACED TEMP SENSOR. MAINT CONTROL NOTIFIED VERIFIED OPS CHECK OF MANUAL TEMP CONTROL RT GOOD.