As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE WORKING ASA TASK CARD NG-36WC-00001 STEP 10 REQUIRES 450 DEG F THERMOSTAT TO BE REPLACED AND CHANGE 390 DEG F PRE COOLER VALVE SENSOR AS PRECAUTIONARY. GROUNDED - YES. REMOVED AND REPLACED #2 ENGINE 450 DEG F THERMOSTAT REF B737-900 AMM 36-11-05-400-801. REMOVED AND REPLACED PRE COOLER VALVE SENSOR REF AMM 36-12-03-400-801. PERFORMED INSTALL TEST FOR 450 SENSOR THERMOSTAT AND PCV SENSOR REF AMM 36-11-05 AND 36-12-03. LEAK CHECKS GOOD.