As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ATB, CLIMB OUT PASSING 24000€™ L OIL TEMP WAS IN THE AMBER RANGE (165°) QRH COMPLETED ACCOMPLISHED AIR TURNBACK. REMOVED AND REPLACED L/H ENG AIR/OIL HEAT EXCHANGER VALVE IAW AMM 79-21-08. OPS AND LEAK CHECKS PERFORMED IAW AMM 71-00-00 NO LEAKS NOTED AND OPS CHECK GOOD. FAULT NO LONGER PRESENT ON ECPS.