Where is the thermostat in a 2004 Toyota Avalon XLS?

In a 2004 Toyota Avalon XLS, the thermostat is located in the engine compartment, specifically near the engine block, where the upper radiator hose connects to the engine. To access it, you typically need to remove the engine cover and the upper radiator hose. The thermostat is housed in a thermostat housing, which is bolted to the engine. Make sure to consult the vehicle's repair manual for specific instructions and safety precautions.