As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
L2 WINDOW OVERHEAT LIGHT ILLUMINATED. RAN QRH LIGHT EXTINGUISHED THEN RE-ILLUMINATES. GROUNDED - YES. CW BITE CK OF WHCU SEVERAL LEGS IN HISTORY SHOW ALL LRU'S FAULTED. CW B737-800 FIM 30-41 TASK 811 FOR SENSOR FAULT. ALL WIRING FROM WHCU TO L2 WDO OHM CKED GOOD. SENSOR READING IS 300 OHM. REMOVED AND REPLACED LEFT SIDE WHCU. ALL TESTS GOOD REF B737-800 AMM 30-41-11-000/400-801. ETOPS GROUND VERIFICATION CKED GOOD.