What is the function of automobile oxygen sensor? Why are some cars equipped with two sensors?

The front oxygen sensor and the rear oxygen sensor decompose and monitor the amount of oxygen in the intake and exhaust. When the oxygen sensor fails, the ECU can't get the information, so it doesn't know whether the injected gasoline is correct.

Automobile oxygen sensor is a key sensing element in the control system of EFI engine, and it is also a key element to control automobile exhaust emission, reduce automobile environmental pollution and improve the fuel combustion quality of automobile engine.

The oxygen sensor detects the oxygen content in the automobile exhaust and feeds it back to the computer. The computer adjusts the fuel injection quantity according to the oxygen sensor to control the exhaust gas to meet the standard. Some cars have two oxygen sensors, because the rear oxygen sensor is generally installed behind the three-way catalytic converter, which mainly detects the working condition of the three-way catalytic converter. Three-way catalyst is to convert harmful gases in tail gas into harmless gases such as carbon dioxide and water. The front oxygen sensor is used to detect the engine combustion, and the rear oxygen sensor is used to detect the working condition of the three-way catalyst and whether the exhaust gas reaches the standard.