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

1 Answers
Byron
07/29/25 9:49pm
Front oxygen sensor and rear oxygen sensor have the following functions respectively: 1. The function of the front oxygen sensor is to detect the oxygen concentration in the engine exhaust gas and provide 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 gas. When a high oxygen concentration is detected in the exhaust gas, it indicates that the engine mixture is too lean; when a low oxygen concentration is detected, it indicates that the engine mixture is too rich. The ECU will adjust the fuel injection quantity accordingly to achieve the optimal air-fuel ratio. 2. The rear oxygen sensor is mainly used to detect the oxygen concentration in the exhaust gas after purification 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.
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