1. Disconnect the ground cable from battery.
2. Remove the collector cover.
NOTE:
Follow the steps below when removing the collector cover.
(1) Pull up the two points at the rear (A).
(2) Pull up the two points at the front (B) while moving them forward.
3. Drain engine coolant. 
4. Disconnect the harness connector from the engine coolant temperature sensor.
5. Remove the engine coolant temperature sensor.