As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JUST AFTER TAKEOFF, NR 4 ENGINE EGT DROP TO ABOUT 50 DEGREES, THEN WOULD NOT READ STABLE FOR ABOUT 10 MINUTES. ENGINE INDICATED 50 DEGREE WARMER AND ON SHUTDOWN AFTER RETURNING TO DTW, THE FADEC FAULT CAME ON. MAINTENANCE REPLACED THE ENGINE DISPLAY PANEL WITH SERVICEABLE UNIT. ALL CHECKS GOOD AT THIS TIME.