As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF WITH ENG NR 2 FIRE LOOP 'B' FAULT INDICATION ON MEL, RECEIVED NR 2 ENGINE FIRE WARNING. ENGINE WAS SHUT DOWN AND AIRCRAFT RETURNED TO DTW WHERE AN UNEVENTFUL LANDING TOOK PLACE. THE NR 2 PYLON LOOP 'B' AND CORE LOOP SUPPORT WERE REPLACED. THE SYSTEMS CHECKED OK AND THE AIRCRAFT WAS DEEMED READY FOR SERVICE.