What are the functions of the front oxygen sensor and rear oxygen sensor?

[Beth]

The functions of the front oxygen sensor and rear oxygen sensor: The front oxygen sensor detects the oxygen concentration in the engine exhaust and provides this information to the ECU in the form of an electrical signal. The ECU then performs closed-loop control of the fuel injection quantity based on the oxygen concentration information in the exhaust. If a high oxygen concentration is detected in the exhaust, it indicates that the engine's air-fuel mixture is too lean; whereas if a low oxygen concentration is detected, it indicates that the mixture is too rich. The rear oxygen sensor primarily detects the oxygen concentration in the exhaust after it has been purified by the three-way catalytic converter. If the data detected by the front and rear oxygen sensors are the same, it indicates that the three-way catalytic converter has failed. Oxygen sensors are installed on the engine exhaust pipe, with the three-way catalytic converter as the boundary: the sensor before the converter is the front oxygen sensor, and the one after is the rear oxygen sensor.