As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK DUE LEFT WING L/E OVERHEAT LIGHT ILLUMINATED DURING CLIMB. LIGHT EXTINGUISHED BY REDUCING THRUST NUMBER 1 ENGINE WITH PYLON VALVE CLOSED. NO PNEUMATIC LEAKS FOUND IN NR 1, NR 2 PYLON OR LEFT WING MANIFOLD. FOUND NR 1 PYLON OVERHEAT DETECTOR INTERMITTENTLY SHORTING. DEACTIVATED PER DISPATCH DEVIATIONS MANUAL. REFERENCE SERVICE BULLETIN 747-26-2066.