As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE TO MSP FROM AMS, AFT CARGO FIRE WARNING ILLUMINATED. CREW FOLLOWED COM PROCEDURE AND DIVERTED TO KEF FOR AN UNEVENTFUL LANDING. VISUAL INSPECTION OF AFT CARGO COMPARTMENT REVEALED NO EVIDENCE OF FIRE. DE-ACTIVATED FIRE DETECTION SYSTEM AND CONTINUED TO MSP WITH PASSENGERS ONLY. REPLACED ALL MID AND AFT CARGO SMOKE DETECTORS. OPERATION CHECKS GOOD.