What Does the O2 Sensor Do in a Car?

December 4, 2023

Every part of a vehicle suffers normal wear and tear over the life of your car, including the oxygen sensor. When this key component of the emissions control system goes bad, it can cause your engine to run inefficiently and even overheat. If you see the check engine light on your dashboard illuminated, it is generally due to an oxygen sensor issue.

The O2 (oxygen) sensor is an electronic device that monitors the amount of unburned fuel in your exhaust fumes as it leaves your vehicle's engine. It tells the vehicle's computer if the internal combustion is burning too rich or if it is running lean with too much air. The information provided by the sensor allows the fuel injection system to make the necessary changes to your vehicle's air/fuel ratio to ensure optimum engine performance.

Like all electronics in your car, the o2 sensor is susceptible to contaminants. Combustion byproducts such as lead, sulfur and fuel additives can cake on the sensor over time and inhibit its ability to send an accurate signal. The o2 sensor is also exposed to high temperatures that can damage it. These factors can all contribute to the o2 sensor becoming faulty, but you can usually spot when this happens because it typically causes engine performance issues. These symptoms can include rough idling, power loss and stalling.


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