As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOS - FL 478 - AT TOP OF CLIMB, FL 230, LEFT ENGINE WOULD NOT RESPOND TO THROTTLE MOVEMENT. OIL TEMPERATURE OF LEFT ENGINE WAS THIRTY TO THIRTY-FIVE DEGREES HIGHER THAN THE RIGHT ENGINE TEMPERATURE. FLIGHT RETURNED TO BOS AND SHUT DOWN ENGINE ON FINAL APPROACH. SET: 4 MINUTES. MAINTENANCE REPLACED THE LEFT ENGINE FUEL CONTROL UNIT. (M)