Where is the Toyota overbearing oxygen sensor?

On the exhaust pipe, near the engine. Some cars have two! Different engines have different oxygen sensors, generally the first one is installed in front of the three-way catalyst, and the second one is behind the three-way catalyst (the second one is only available in some cars).

The main function of oxygen sensor is to detect the oxygen content in exhaust gas, so as to control the fuel injection quantity. Damage will lead to excessive fuel injection and high fuel consumption, which will also affect water temperature sensing.