Fuel injection has made operating a gasoline-engined vehicle exceedingly simple. They start easily in cold weather, offer better performance and achieve better gas mileage. Fuel injection requires a complicated array of sensors, valves and electronics to function properly. These components may fail over the lifespan of a vehicle, reducing the mileage and performance of the engine or causing the engine not to run at all.
The oxygen sensor works in conjunction with the engine control module and fuel injectors to provide the engine with the correct air-fuel ratio. Gasses passing through the exhaust manifold react with the oxygen sensor, which produces an electrical signal between 0.1 and 0.9 volts. A 0.1 volts signal means there is a high oxygen content in the exhaust and thus a lean air-fuel mixture. A 0.9 volts signal means a low oxygen content and therefore a rich air-fuel mixture.
The oxygen sensor on a Chevrolet S-10 in-line four-cylinder engine is located in either the exhaust manifold or head pipe. It will resemble a small metal plug screwed into the manifold with a wiring harness connected to the end.
Disconnect the wiring harness from the oxygen sensor by pulling the plastic electrical connector from the steel sensor. Be careful when doing so, as plastic connectors can become brittle with age and break.
Spray a penetrating oil such as WD-40 onto the threads of the oxygen sensor and allow them to soak for five minutes.
Use a socket connected to a long breaker bar to gently loosen the sensor, and then remove it. Remember to clean the threads on the exhaust manifold.
