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The first indication of a problem with your vehicle’s oxygen sensor is often when the “check engine” light comes on. Failing sensors cause jerky movements, trouble starting, and reduced fuel efficiency if they aren't replaced. Oxygen sensors are necessary for vehicles to combine the proper ratio of gas and oxygen into fuel. Depending on the make and model, your vehicle could have 2 to 4 of them to replace. Even if you have minimal experience with cars, they aren’t hard to replace. Twist off the old sensors, install the new ones, and then appreciate how much better your vehicle runs.
Steps
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Use an OBD code scanner to detect the broken sensor. An OBD code scanner is a device that plugs into a port on the car’s dashboard. It retrieves an error code from the onboard computer, which shows you the reason for the check engine light . Each error code corresponds to a different part of the vehicle.- You can buy a scanner online or at most auto parts stores. If you don’t have one, you could take your vehicle to an auto parts store or mechanic to have them detect the error code.
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Let the engine cool before attempting to remove a sensor. The sensors are located along the exhaust system, which gets very hot when the vehicle is in use. Touching the engine, for instance, is dangerous. Turn the vehicle off and give it about 30 minutes to cool. [1] X Expert Source Hovig Manouchekian
Auto Repair & Design Specialist Expert Interview. 23 February 2021. If you need to touch a component before you are sure it is cool, wear protective gear.- Have a heat-resistant glove, such as a welder’s mitt. Also, put on long-sleeved clothing and safety glasses for additional protection.
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Jack up the vehicle if you need to reach a sensor under it. Park the car on a hard, flat surface. Prevent the wheels from moving by wedging chocks behind them. Then, slide a jack underneath one of the vehicle’s jack points. After lifting it up, place a jack stand there to keep the car elevated.- Starting around 1994 and 1995, manufacturers started making vehicles with 2 oxygen sensors. The second sensor is only accessible by crawling underneath the vehicle.
- Lifting a car is dangerous, so make sure it is stable before looking for the sensor. If you aren’t comfortable working under a car, ask a mechanic for help.
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Locate the oxygen sensor underneath the hood or vehicle. Look for a part that looks like a spark plug with a thick, black cable coming out of it. The first sensor will always be next to the motor in the engine compartment. It will be on the exhaust pipe leading from the motor toward the back of the vehicle. Most cars these days also have a second sensor behind the catalytic converter, which looks like a metal cylinder on the exhaust line and is found right behind the front wheels. [2] X Research source- Most vehicles made after the year 2000 actually have 4 sensors. Each vehicle has 2 sensors near the motor and 2 near the catalytic converter.
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Disconnect the electrical connection to the oxygen sensor. Follow the cable away from the end of the sensor plugged into the exhaust line. It will end in a plastic plug inserted into an outlet. To remove it, locate the small tab on the end of the plug. While pushing the tab down, pull the plug back by hand. [3] X Research source- If you’re having a hard time unplugging the sensor wire, push the tab down with a flathead screwdriver as you pull the connection back with your free hand.
- Avoid attempting to cut and then solder the wires to the new oxygen sensor. With modern sensors, soldering causes the wires to stop working correctly.
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Spray some penetrating oil onto the sensor to loosen it. Worn-out sensors can be tough to remove, but a good penetrating oil helps ensure they come out. Add the lubricant to the opening where the sensor plugs into the exhaust line. Wait about 10 minutes for the oil to soak in before trying to unscrew the sensor. You may need to apply the oil a few times before you are able to get the sensor out. [4] X Expert Source Hovig Manouchekian
Auto Repair & Design Specialist Expert Interview. 23 February 2021. [5] X Research source- Another way to treat a stubborn oxygen sensor is to heat up its base and threads. Use a heat gun instead of a torch to lightly warm the sensor until you can remove it. A heat gun doesn’t have flames, so it’s safer than a torch, but be careful and protect yourself with proper safety gear.
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Unscrew the oxygen sensor using a ratchet wrench. The easiest way to detach the sensor is by using a 3 ⁄ 8 in (0.95 cm) ratchet wrench fit with a 7 ⁄ 8 in (2.2 cm) oxygen sensor socket. If you don’t have one, try using an open end wrench. Fit the wrench over the sensor where it plugs into the exhaust line. Turn it counterclockwise to loosen it, and then finish unscrewing it by hand. [6] X Research source- All of the tools you need are available online or at most auto parts stores. You could also check to see if your local auto parts stores has a tool rental program.
- If the sensor feels stuck in place, don’t force it. Apply more penetrating oil as needed to avoid damaging the vehicle. If it’s too tough to remove, take it to a professional.
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Select a new oxygen sensor that is the same as the old one. Use the make and model of your car to find the correct oxygen sensor. For example, search for a Toyota Prius to find the exact sensor used in a new Prius. Make sure the new sensor is the same size and shape as the old one. It should also be the same brand.- You may find off-brand sensors at a cheaper rate, but avoid them for the sake of your vehicle. The only sensor model guaranteed to work with the vehicle’s onboard computer is the same one the manufacturer used.
- If you are able to, contact an auto parts store before attempting to change the sensor. You could also take the old sensor to a store if you can get a ride there.
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Add a small amount of anti-seize to the new sensor. New sensors come packed with a bag of bronze gel. You may be wondering what that strange goo is at first, but it’s a very important lubricant. Cut open the bag, then use a glove or clean rag to spread a small amount of the lubricant onto the new sensor’s threads. The threads are the grooves in the metal ring near the tip of the sensor. [7] X Expert Source Hovig Manouchekian
Auto Repair & Design Specialist Expert Interview. 23 February 2021. [8] X Research source- To avoid any problems with the anti-seize, wear a glove when applying it by hand. If you get it on your skin, it isn’t likely to harm you, but thoroughly wash your hands afterward.
- You do not need a lot of the gel. As long as you get some of it into the thread grooves, the sensor will fit properly in the exhaust line.
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Turn the sensor clockwise to secure it on the exhaust line. Fit the tip of the sensor into the hole on the exhaust line. Make sure it is centered and goes in smoothly as you begin rotating it clockwise by hand. Once it is tightly in place, use an oxygen sensor socket or open end wrench to give it a final turn. [9] X Research source- The new sensor doesn’t have to be tightened as much as possible. In fact, overtightening the sensor could strip the threads, making it impossible to remove!
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Plug the electrical connector back into the vehicle. Modern oxygen sensors come equipped with a connected electrical cable, so you don’t have to do any additional work. The cable will be hanging from the free end of the sensor. Plug it into the outlet port close to the exhaust line. [10] X Research source- Push the plug in until it snaps into place. Make sure the cable isn’t touching the engine or other parts that heat up when the vehicle is in use.
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Start the car to see if the problem is fixed. The new sensor makes a big difference. It causes your vehicle to burn fuel more efficiently, It sounds better, runs more smoothly, and uses less fuel. If the check engine light was on, it most likely will turn off as well. Take the car out on the road to make sure it stays off. [11] X Research source- In some vehicles, you may need to clear the check engine light manually. Shut off the engine, then turn the car’s power on using the ignition key. Use the delete feature on an OBD code scanner to reset the light.
- Disconnect the battery or take the vehicle to a mechanic for additional ways to shut off the check engine light.
- If the check engine light comes back on, either the oxygen sensor wasn’t installed correctly or your vehicle has another problem.
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Expert Q&A
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QuestionWhat is anti-seize?Hovig Manouchekian is an Auto Repair and Design Specialist and the Manager of Funk Brothers Auto, a family-owned business operated since 1925. With over 30 years of experience in the automotive industry, Hovig specializes in the process of auto repair and maintenance. He is also very knowledgeable in common automotive issues and needs including engine repair, battery replacement, and windshield accessory and maintenance. Hovig's knowledge and hard work have contributed to Funk Brothers Auto winning Angie's List Super Service Award for five consecutive years.New oxygen sensors often come with an anti-seizing or anti-corrosion lubricant that should be applied to the sensor when it's being installed. That will keep the threads on the sensor from seizing, which happens when temperatures fluctuate on the vehicle.
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QuestionHow long does it take to replace an O2 sensor?Community AnswerIt should only take a few minutes depending on your experience level.
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QuestionWill a vehicle run without sensors?Community AnswerIt will run, but poorly since the ECU won't know how efficient parts of the exhaust are. It won't sound very good, and it won't run very well, so I don't recommend it.
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Tips
- To keep your car running smoothly, replace all the sensors at once. If one fails, chances are the other ones will fail soon too, so try to keep them on the same maintenance schedule.Thanks
- Most auto parts stores have code readers you can borrow to detect a faulty sensor. The employees will even help you use it, although they will also try to sell you replacement sensors.Thanks
- To figure out if a bad sensor is causing a lit check engine light, use an OBD-II code reader. It plugs into your car and gets error codes from the onboard computer to find the problem.Thanks
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Warnings
- Always allow the engine and exhaust system to cool down before you begin work to prevent accidentally burning yourself.Thanks
- Crawling under a car is dangerous, so practice good safety by using jack stands.Thanks
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Things You'll Need
- New oxygen sensors
- Jack
- Jack stands
- 3 ⁄ 8 in (0.95 cm) ratchet wrench or open end wrench
- 7 ⁄ 8 in (2.2 cm) oxygen sensor socket
- Penetrating oil
- Auto diagnostic scanner/reader (optional)
- Flathead screwdriver (optional)
References
- ↑ Hovig Manouchekian. Auto Repair & Design Specialist. Expert Interview. 23 February 2021.
- ↑ https://www.youtube.com/watch?v=1ZBjHy76Pwc&feature=youtu.be&t=62
- ↑ https://www.youtube.com/watch?v=_Kr-c8eBl5E&feature=youtu.be&t=48
- ↑ Hovig Manouchekian. Auto Repair & Design Specialist. Expert Interview. 23 February 2021.
- ↑ https://www.popularmechanics.com/cars/how-to/a7140/how-to-replace-an-oxygen-sensor/
- ↑ https://www.youtube.com/watch?v=Yk6AM4wqm-0&feature=youtu.be&t=528
- ↑ Hovig Manouchekian. Auto Repair & Design Specialist. Expert Interview. 23 February 2021.
- ↑ https://www.popularmechanics.com/cars/how-to/a7140/how-to-replace-an-oxygen-sensor/
- ↑ https://www.youtube.com/watch?v=1ZBjHy76Pwc&feature=youtu.be&t=155
About This Article
Article Summary
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If your car’s “check engine” light is on, the problem may be with your oxygen sensor. To make sure, plug an OBD code scanner into your car’s dashboard, and check the error code that it gives you to see if it shows a problem with your oxygen sensor. You can find OBD error codes online, or see your mechanic for more information. Once you’ve confirmed that you need to change the oxygen sensor, let your engine cool for at least 30 minutes before you try to handle it. If your car has two or more oxygen sensors, you may also need to jack up your vehicle so you can reach any sensors located under the car. To find the oxygen sensor, look for a part that resembles a spark plug with a thick, black cable attached to it. Most cars have a sensor located on the exhaust pipe next to the motor inside the engine compartment. You might find another sensor under the car, behind the catalytic converter. In more recent cars, look for 2 sensors in each of these locations. Once you find a sensor, follow the black cable emerging from it until you find the plug connecting it to the car’s electrical system. Push down the small plastic tab at the end of the plug and pull the plug out of its outlet to disconnect it. If the end of the cable that’s attached to the exhaust line is corroded or too stiff to unscrew easily, spray it with a penetrating oil such as Kroil or Liquid Wrench, then let it sit for a few minutes. Unscrew the sensor with a 3/8 inch (0.95 cm) ratchet wrench fit with a 7/8 inch (2.2 cm) oxygen sensor socket. Turn the wrench counterclockwise until the old sensor is loose enough so that you can finish unscrewing it by hand. If possible, select a new sensor that is the exact same size, shape, and brand as the new one. Apply a small amount of anti-seize lubricant to the threaded end of the sensor and wipe the threads with a rag to spread the lubricant evenly. Most new sensors come with a small package of this lubricant, so you won’t have to buy it separately. Fit the threaded end of the sensor into the port on the exhaust line and screw it in clockwise by hand, then tighten it with a wrench fit with an oxygen sensor socket. Finally, plug the electrical cable back into the outlet next to the exhaust line. Turn your car on and take it for a drive to make sure your vehicle is running smoothly and the check engine light is off.
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Reader Success Stories
- "I had my 2000 Ford Taurus diagnostic check at Auto Zone, and it read the car had a bad headed oxygen sensor. Therefore I looked up the information. I do like the way this explains the way to remove it and how to replace it with step-by-step instructions, which really helped me on how to do it myself. Thanks again for showing good results on this page." ..." more
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"I had my 2000 Ford Taurus diagnostic check at Auto Zone, and it read the car had a bad headed oxygen sensor. Therefore I looked up the information. I do like the way this explains the way to remove it and how to replace it with step-by-step instructions, which really helped me on how to do it myself. Thanks again for showing good results on this page."
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"The steps you provide are the best I have found on the internet for trying to find and repair the specific O2 sensors that I have found. Thanks for the simple instructions you provide."
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"I followed your instructions and replaced two oxygen sensors successfully. Thank you."
"It helped me understand more about the oxygen sensor part and how to remove it."
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