As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK DUE TO LEFT FIRE LIGHT ILLUMINATED ON CLIMB-OUT. AFTER LEFT OVERHEAT DETECTOR SWITCH WAS MOVED TO FIRE, THE LIGHT WENT OUT. ON ENGINES SHUT DOWN THE PROBLEM STILL EXISTED. REMOVED AND REPLACED NR 1 ENG LOWER FIRE LOOP PER MM.