What is an oxygen sensor?

Most new cars now come with Oxygen sensors? Many car owners haven’t even heard of oxygen sensors until their mechanic tells them that the sensor needs replacing.

So.. what is the oxygen sensor and what does it do?

The sensor is part of the emissions control system and feeds information to the cars onboard computer. The sensor helps the onboard computer to run the engine as efficiently as possible with the lowest emissions as possible.

All engines burn fuel in the presence of oxygen and the ratio of air and fuel is important for efficiency and CO2 emissions. Different fuels have different ratios. If there is less air and more fuel then there will be fuel left over after combustion which is not terribly efficient and the unburnt fuel will create high emissions. If there is more air and less fuel this will result in poor performance, high nitrogen pollutants and can even possibly result in engine damage.


The Oxygen sensor resides in the engine exhaust system and detects the ratio of air and fuel by way of a chemical reaction. This reaction will create a signal for the onboard computer which adjusts the amount of fuel entering the engine accordingly, aiming to achieve a perfect balance of fuel and oxygen. The balance can be impacted by a number of factors such as the load on the engine, the atmospheric pressure, the temperature (outside, and of the engine), altitude, etc.

It is important to replace the sensor when it fails as the vehicle will not be operating efficiently and this will cost more in the long term as the car will probably burn more fuel that it needs to.

We have a wide variety of cheap oxygen sensors on our website. You can rest assured that you are getting one of the most competitively priced oxygen sensors in the market today.

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