As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW RETURNED TO RAMP AFTER INDICATION OF FIRE IN THE NR 1 ENGINE. MAINTENANCE VERIFIED THAT THE WARNING WAS FALSE AND WAS CAUSED BY CONTACT BETWEEN THE FORWARD FIRE DETECT LOOP AND A DISCONNECTED O/B HEATED INTAKE LIP FLEX TUBE. MAINTENANCE REPLACED THE FORWARD FIRE DETECT LOOP AND RECONNECTED THE FLEX DUCT.