As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INTERMITTENT PROBLEM WITH LEFT ENGINE FIRE DETECTION SYSTEM. THE NR 1 ENGINE OVERHEAT MESSAGE WAS A FALSE INDICATION. BOTH OF THE NR 1 ENGINE FIRE LOOPS WERE INSPECTED AND OPS CK'D WITH NO DISCREPANCIES FOUND. DUE TO LEFT CARD FAULT INDICATION FROM CMC, THE NR 1 ENGINE FIRE DETECTION CARD WAS REPLACED.