How to Replace an Oxygen Sensor

Oxygen sensors are one of the most important components on a modern vehicle’s engine management system. They are responsible for monitoring the air fuel mixture of the engine, and their readings affect important engine functions such as timing and air fuel mixture.

Over time, with normal use, oxygen sensors can begin to function with a delayed response, and they will eventually fail. Typical symptoms of a failed oxygen sensor are decreased engine performance, decreased fuel efficiency, rough idle, and in certain cases, even misfires. Usually a failed oxygen sensor will also set off a check engine light, specifying which sensor on what bank has failed.

In most cases, replacing an oxygen sensor is a relatively straightforward procedure that usually only requires a few tools. In this step by step guide, we will go over what removing and replacing an oxygen sensor typically entails.

Part 1 of 1: Replacing an oxygen sensor

Materials Needed

scanning tool

Step 1: Identify the faulty sensor. Before beginning, connect the OBD II scan tool to the vehicle and read the codes to determine which specific oxygen sensor has failed and needs to be replaced.

Depending on the engine design, vehicles can have multiple oxygen sensors, sometimes on both sides of the engine. Reading the trouble codes will tell you exactly which sensor is in need of replacing — either the upstream (top) or downstream (bottom) sensor — and on what bank (side) of the engine.

vehicle raised on jack stands

Step 2: Raise the vehicle. Once the faulty sensor has been identified, raise the vehicle and secure it on jack stands. Be sure to raise the vehicle on the side which you will allow you to access the oxygen sensor that needs to be replaced.

person disconnecting the oxygen sensor

Step 3: Disconnect the oxygen sensor connector. With the vehicle raised, locate the faulty oxygen sensor and disconnect the wiring harness connector.

person using tools to remove the oxygen sensor

Step 4: Remove the oxygen sensor. Using the oxygen sensor socket or the appropriate size open end wrench, loosen and remove the oxygen sensor.

side by side comparison of the oxygen sensor

Step 5: Compare the faulty oxygen sensor with the replacement sensor. Compare your old oxygen sensor with your new replacement to ensure the correct fitment.

new oxygen sensor installed

Step 6: Install the new oxygen sensor. Once fitment has been verified, install your new oxygen sensor, and connect the harness.

person using a scan tool to erase the trouble codes

Step 7: Clear the codes. Once the new sensor has been installed, it is time to clear the codes. Connect the OBD II scan tool to the vehicle and clear the codes.

person inserting and turning key in the ignition

Step 8: Start the vehicle. Once the codes have been cleared, remove and reinsert the key, and then start the vehicle. The check engine light should now be gone, and the symptoms you were experiencing should be alleviated.

In most vehicles, replacing an oxygen sensor is a simple procedure that requires only a few tools. However, if this is not a task you are comfortable doing on your own, this is something that any professional technician, such as one from YourMechanic, can take care of quickly and easily.

Next Step

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Recent Oxygen Sensor Replacement reviews

Excellent Rating


Rating Summary


12 years of experience
49 reviews
12 years of experience
Chevrolet Silverado 1500 V8-4.8L - Oxygen Sensor Replacement (Front/Upper/Upstream, Rear/Lower/Downstream) - Moreno Valley, California
very knowledgeable and honest , professional and clean explain everything to me and answer all m,y question
Scion tC - Oxygen Sensor Replacement (Rear/Lower/Downstream) - Sun City, California
Arrived in a timely manner, was very professional and knowledgeable about any questions. Would definitely recommend to anybody (family, friends, etc) looking for a mechanic!


11 years of experience
146 reviews
11 years of experience
Honda CR-V L4-2.4L - Oxygen Sensor Replacement (Front/Upper/Upstream, Rear/Lower/Downstream) - Frisco, Texas
I have not seen a more sincere and hard working person than Joel. This, on top of his great skills and know-how of working with an automobile and a very friendly, likeable personality. Unfortunately, it took multiple attempts to fix the Check Engine light on my vehicle. The car needed O2 sensor replacement but due to a couple of reasons the problem was not getting fixed. So Joel would come, run the tests, fix the problem, do the test drive, and leave thinking the problem has been resolved only to find out from me later that the Check Engine light is back on. However, Joel followed up patiently with me over the course of couple of months to ensure that the problem was fully resolved, even if it took him a couple of visits. Well, he has my business from now on and full trust for my cars! Thank you, Joel!
Ford Expedition - Oxygen Sensor Replacement (Front/Upper/Upstream, Rear/Lower/Downstream) - Denton, Texas
Joel showed up right on time. Replaced O2 sensors on my Ford Expedition. Ran a diagnostic as well & verified fuel trims etc. Was in and out within an hour. Ensured my driveway was clean when he left and did not leave any mess. I was very pleased with his professionalism. Definitely recommend Joel for auto repair.


30 years of experience
873 reviews
30 years of experience
Toyota Camry V6-3.5L - Oxygen Sensor Replacement (Rear/Lower/Downstream) - Orlando, Florida
Mr. James dis an awesome job on my 2007 toyota camry. He was punctual and professional. He fixed the problem very quick.
Toyota Avalon - Oxygen Sensor Replacement (Front/Upper/Upstream, Rear/Lower/Downstream) - Apopka, Florida


17 years of experience
217 reviews
17 years of experience
Ford F-150 V8-5.4L - Oxygen Sensor Replacement (Front/Upper/Upstream) - Cedar Park, Texas
Shane is great. I will be calling on him soon on other vehicles I own. Thank you Shane for a great job.

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