What is the working principle of an oxygen sensor?

[VonPaul]

The oxygen sensor is a crucial sensing component in the electronic fuel injection engine control system. It plays a key role in controlling vehicle exhaust emissions, reducing environmental pollution caused by automobiles, and improving the fuel combustion quality of car engines. In engines equipped with three-way catalytic converters to reduce exhaust pollution, the oxygen sensor is an indispensable component. When the air-fuel ratio of the mixture deviates from the theoretical air-fuel ratio, the purification capability of the three-way catalyst for CO, HC, and NOx drops sharply. Therefore, an oxygen sensor is installed in the exhaust pipe to detect the oxygen concentration in the exhaust and send feedback signals to the ECU. The ECU then adjusts the fuel injection amount of the injector accordingly, keeping the air-fuel ratio of the mixture near the theoretical value.