As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - LEFT ENGINE FIRE LOOP ONE AND TWO AND LEFT 1 AND LEFT 2 CIRCUIT OVERHEAT INDICATION ON. EMERGENCY DECLARED RETURNED DFW WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND FIRE LOOPS 1 AND 2 CONNECTED INCORRECTLY. RECONNECTED FIRE LOOPS 1 AND 2. REPLACED LEFT ENGINE FIRE WARNING CARD. SYSTEM GROUND CHECK NORMAL OPERATION.