As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE ITT SPIKED TO 800° IN FLIGHT. TRIED TO CONTROL TEMP WITH THROTTLE, BUT WHEN WE DESCENDED TO 5000', ITT EXCEEDED 760°. SHUTDOWN ENGINE, BUT ITT NEVER DROPPED BELOW 500° - EVEN WHEN ON GROUND. FOUND T1 SENSOR HARNESS OUT OF LIMITS AND ERRATIC. INSTALLED NEW T1 HARNESS ASSY. AND THERMOCOUPLE HOUSING IAW MM 77-20-01. PERFORMED 5PT PERFORMANCE RUN IAW MM 71-00-00. NO DEFECTS NOTED. OPS CHECK GOOD.