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Q: Where Are the Oxygen Sensors Typically Located?

A: Oxygen sensors are located in the vehicle’s exhaust system. Most vehicles are equipped with two oxygen sensors. An upstream oxygen sensor is mounted before the catalytic converter. Meanwhile, a downstream sensor is mounted after the cat-con.

upstream and downstream oxygen sensor
An upstream oxygen sensor is mounted before the catalytic converter. Meanwhile, a downstream sensor is mounted after the cat-con.

Oxygens sensors measure the amount of oxygen in the exhaust. Your vehicle’s powertrain control module (PCM) uses the data from these sensors to calculate the proper amount of fuel needed by the engine. The input from the downstream sensor is also used to monitor the health of your catalytic converter.

Tips on How to Access the Oxygen Sensors

Before anything else, you’ll have to start your vehicle and let it warm up. After that, you can turn off the ignition and open the hood.

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Make sure that you follow safety protocols when doing any oxygen sensor repair. Be careful not to burn yourself during the process. Wear a heat-resistant glove, such as a welder’s mitt. You can also wear long-sleeved clothing and safety glasses for additional protection.

You’ll have to disconnect the battery and jack up your ride. In most modern vehicles, you can find two sensors near the motor and two sensors near your catalytic converter. An oxygen sensor resembles a spark plug. It looks like a small metal device with wires coming out of it.

If you’re accessing the oxygen sensors because of a fault code, you’d have to be sure which particular sensor needs to be inspected and/or replaced. You can refer to the owner’s manual to know more details about the oxygen sensors installed in your specific make and model.

Once you locate the oxygen sensor you’re trying to repair, find the electrical connector and disconnect it by pressing the retaining tab and pulling the terminal. You can unscrew the oxygen sensor using a wrench.

About The Author
CarParts Research Team
Written By Research Team

Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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