How to Change an O2 Sensor on Cars

by Contributing Writer; Updated June 12, 2017

The Toyota car has at least two oxygen sensors. The newer ones may have up to four. Figuring out which one needs to be replaced may be more difficult than crawling underneath and replacing the sensor. Oxygen sensors were incorporated into the exhaust systems to monitor the amount of oxygen in the burning fuel. A high or lean variance during the operation of the Toyota car can lead to a diagnostic trouble code reported by one or more of the sensors to the computer of the SUV and trigger a "check engine" warning light on the dashboard instrument panel.

Under The Hood:

 How to Change an O2 Sensor on a Saturn Ion

Place the jack underneath the car and lift it up in the air. Set all four corners of the car down on jack stands, making sure that you have enough room to crawl underneath the car.

Locate the oxygen sensors on the exhaust. These are cylindrical pieces, similar to spark plugs in look, that stick out of the exhaust tubing three inches and have a wire leading out of them. These are the only electrical connections on the exhaust. One sensor is located at the base of the exhaust manifold where it contacts the exhaust system, and another approximately two feet down the exhaust tubing from the flange. Disconnect the electrical connection on the oxygen sensor that you want to replace with your hands.

Attach the oxygen sensor socket to the 3/8-inch ratchet, then slide the socket over the oxygen sensor. Remove it using the ratchet, then discard the old sensor.

Apply the anti-seize compound to the threads of the replacement oxygen sensor. Make sure you do not touch the sensor head itself with the compound. Thread the replacement sensor into the exhaust first by hand, then tighten it using the ratchet and socket. Reattach the electrical connection to the oxygen sensor, then use the jack to lower the car off of the stands.

Items you will need

  • Jack

  • Jack stands

  • Oxygen sensor socket

  • 3/8-inch ratchet

  • Anti-seize compound

  • Replacement oxygen sensor

 How to Replace the o2 Sensor on Hyundai Santa Fe

Let the Santa Fe cool down. If you have just run the engine, the entire system should cool for several hours before attempting to work on the exhaust system where the O2 sensors are located.

Place the floor jack under the Santa Fe and jack up on the front jack point located behind the radiator.

Place a jack stand under each of the front pinch welds located directly under the driver and passenger side doors on the underside of the vehicle.

Locate the O2 sensors. There are four oxygen sensors on the Santa Fe (usually). There are 2 sensors "upstream" (on the manifold) and 2 "downstream" (one on each converter for the manifold).

Unplug the electrical wiring that connects to the O2 sensors. These are plug-style connectors. Squeeze the release tab and pull them off the sensor.

Unbolt the O2 sensor as you would any other bolt, but use an O2 sensor tool. Turn the O2 sensor counterclockwise to remove it.

Place a small dot of anti-seize compound on the new O2 sensors and install them. Installation is the reverse of removal.

Items you will need

  • Jack

  • Jack stands

  • O2 sensor tool

  • Anti-seize compound

 How to Replace an O2 Sensor in a Toyota 4Runner

Drive the Toyota 4Runner up onto the car ramps carefully on a flat surface. Apply the parking brake. Place a wheel chock behind one of the rear tires.

Grab all of your tools, put on the safety glasses, and crawl under the Toyota 4Runner on a creeper. Locate the sensor you need to replace. These sensors are bolted into the exhaust system on 4Runners. They are located up high on the front exhaust pipe near the manifold and downstream on the exhaust system near the catalytic converter.

Remove the two nuts on the flange of the oxygen sensor you're replacing. It's not uncommon on the 4Runners for these nuts to be severely corroded and will no longer be able to remove with a socket. An extractor socket pounded on with a hammer or a pair of vise grip pliers squeezed against the nut to break it loose enough to un-thread it by hand is usually all it takes.

Follow the oxygen sensor wire to the plug connection. It'll be about 7 inches away from the sensor. Unplug the connection by pressing in on the clip lock with a flathead screwdriver and separate the plug. Remove the old sensor and remove the old gasket from the oxygen sensor flange on the exhaust pipe.

Clean the threads of each stud using an 8x1.25 millimeter re-threader or die. Install the new gasket onto the flange and place the new oxygen sensor into the porthole. Place the lock washers and nuts onto the studs of the flange and tighten with a ratchet and a socket.

Plug the oxygen sensor wire back into the plug connection.

Gather up all the tools and crawl out from under the 4Runner. Remove the wheel chock, release the parking brake and lower the 4Runner off of the ramps.

Items you will need

  • Direct-fit quality aftermarket or Toyota replacement oxygen sensor and gasket

  • Vise grip pliers

  • Extractor socket set

  • 3/8 inch drive ratchet

  • 3/8 inch drive socket set

  • Small ball peen hammer

  • Safety glasses

  • Flathead screwdriver

  • Creeper

  • Car ramps

  • 8x1.25 millimeter re-threader/die

  • Wheel chock

  • 8 millimeter width by 1.25 millimeter thread pitch nuts (2 per sensor)

  • 8 millimeter lock washers (2 per sensor)

 How to Replace the O2 Sensor in a Cadillac

Place the Cadillac in "Park" and turn off the engine. Leave the vehicle to cool for about 15 minutes. This will ensure the sensor is still warm without being too hot to touch, which is ideal for removal and replacement.

Open the hood and locate the oxygen sensor, which is on the exhaust manifold. Follow the exhaust pipe until you reach a small cylinder plug component with a wire coming out of the very top of it. This is the oxygen sensor.

Remove the wire by pulling it out of the current sensor and place it safely to the side.

Remove the oxygen sensor from the exhaust manifold, using an oxygen sensor socket with a socket wrench. The oxygen sensor socket fits snugly and is easiest to use when removing the sensor. Turn the wrench counterclockwise until the sensor is loose enough to remove easily. Remove the sensor by pulling it straight off the manifold.

Align the replacement oxygen sensor on the manifold. Secure the new sensor, using the socket wrench and oxygen sensor socket. Insert the wire into the new sensor; it will click once it's secured into the sensor. The sensor has now been replaced and is ready for use. Close the hood of the Cadillac.

Items you will need

  • Socket wrench

  • Oxygen sensor socket

 How to Replace a O2 Sensor on a Honda Accord

Raise the Accord onto jack stands. Lift up the front of the accord with a floor jack using the front jack point. Slide the jack stands under the front pinch welds and lower the Accord onto the stands.

Pull the O2 sensor leads off the factory wiring harness.

Remove the O2 sensor by turning it counterclockwise with a O2 sensor socket and socket wrench.

Install the new O2 sensor. Reverse the order of these instructions to reassemble.

Items you will need

  • New O2 sensor

  • O2 sensor socket

  • Socket wrench

  • Jack

  • Jack stands

 How to Change the O2 Sensor on a Lexus LS430

Determine which oxygen sensor needs to be replaced. Plug a code reader or scan tool into the diagnostic link connector located beneath the driver's side dashboard. Turn the Lexus SC430 ignition to the "accessories" position. Follow the directions of the code reader or scan tool to discover which sensor has failed. Bank one-sensor one is the forward-most (towards the engine) sensor located on the same side as the number one cylinder. Bank one-sensor two is downstream on the same side, near the rear catalytic converter. Respectively, the two sensors for bank two are positioned in the same way on the opposite side of the engine and exhaust.

Lift the SC430 if you're replacing one of the number two sensors. The number one sensors may be easier to access from the engine compartment on either side of the engine by the manifold.

Follow the wire harness of the sensor you're going to replace until you find the plug. It will be eight or nine inches away from the sensor. Disconnect the plug of the sensor from the plug of the wire harness.

Use the oxygen sensor socket and a flex-head ratchet to remove the sensor from the exhaust porthole. A 22 mm wrench can also be used, but the amount of room available may restrict its effectiveness. Turn the sensor counterclockwise from the exhaust porthole to remove. Remove the sensor.

Thread the new direct-fit sensor into the exhaust porthole by hand to assure you're not cross-threading it. Snugly tighten the sensor with the socket and ratchet (or the 22 mm wrench). Do not over-tighten the sensor because the threads on the sensor can easily strip.

Plug the sensor wire plug back into the wire harness plug.

Rescan the PCM using the code reader or scan tool. Follow the directions to erase the code to clear the check engine light.

Items you will need

  • Lexus SC430 repair manual

  • Code reader/scan tool

  • Oxygen sensor socket and a flex-head ratchet

  • Replacement oxygen sensor (direct-fit only)

  • Car lift (optional)

 How to Replace the O2 Sensor in a Jaguar

Locate the O2 sensor directly in front of the catalytic converter on the driver's side of the Jaguar. The O2 sensor is white and has a green wire protruding from it. Use the replacement sensor as a visual aid.

Trace the wire protruding from the sensor to the wiring harness it connects to. Disconnect the wire from the harness.

Remove the sensor from the Jaguar's exhaust pipe with a box-end wrench.

Thread the new sensor into the hole in the exhaust pipe with your fingers then tighten the sensor with the box-end wrench.

Reconnect the green wire on the new O2 sensor to the wiring harness.

Inspect the passenger side of the vehicle for a second O2 sensor. If your Jaguar has a dual exhaust, it will have a second sensor just above the catalytic converter on the passenger side. Complete Steps 2 through 5 with the second sensor.

Items you will need

  • Wrench set

 How to Replace the O2 Sensor on a 2003 Suburban

Removing the Oxygen Sensor

Drive your Suburban for about 20 minutes to bring the engine to operating temperature. This will ease the oxygen sensor’s threads from the exhaust pipes and make it easier to remove.

Release the parking brake, shift the transmission to neutral and detach the ground battery cable using a wrench.

Lift the front of your Suburban on a pair of portable ramps and jack up the rear on jack stands, using a floor jack.

Locate the oxygen sensor you want to replace. You will find the two upstream sensors on the front exhaust pipes, located between the exhaust manifold and the catalytic converter. Usually they are mounted on the pipes by the side of the transmission. You will find the two downstream sensors on the exhaust pipes that go from the rear of the catalytic converters to the rear of the vehicle. Usually they are mounted close to the converters.

Follow the electrical wire attached to the back of the oxygen sensor to find the electrical connector. Detach the small plastic stick (connector position assurance or CPA) securing the oxygen sensor connector to the plug and unplug the sensor connector.

Unscrew the oxygen sensor from the exhaust pipe with a ratchet, ratchet extension and an oxygen sensor socket.

Installing the New Oxygen Sensor

Apply anti-seize compound to the threads of the new sensor, if the new unit does not come with the compound already applied. This will help remove the sensor next time you need to replace it.

Hand-start the new sensor into the exhaust pipe. Tighten the sensor to 30 ft-lbs. (41 Nm), using a torque wrench, ratchet extension and oxygen sensor socket.

Plug in the sensor electrical connector and secure the connection with the CPA.

Lower the rear of your Suburban off the jack stands with the floor jack and move the vehicle off the ramps.

Attach the ground battery cable with the wrench.

Items you will need

  • Wrench

  • 2 portable ramps

  • 2 jack stands

  • Floor jack

  • Ratchet

  • Ratchet extension

  • Oxygen sensor socket

  • Anti-seize compound

  • Torque wrench

 How to Replace an O2 Sensor on a 2003 Toyota Tundra

Removal

Park the truck on a level surface and set the parking brake. Lift the hood and support it with the hood prop rod. Allow the engine to cool completely before continuing.

Lift the front of the truck into the air with a floor jack and place jack stands under the front frame rails. Lower the floor jack until the truck rests securely on the jack stands. Follow the exhaust manifold toward the fire wall on either side of the engine bay to locate the upstream oxygen sensors. Follow the oxygen sensor pigtail to where it connects to the engine wiring harness. Squeeze the locking tab and separate the connectors, if replacing either upstream oxygen sensor.

Lie down under the truck and position yourself just behind the front wheels. Look at the exit points of the catalytic converter to locate the downstream oxygen sensors on the left or right exhaust pipe. Follow the pigtail to its connection at the vehicle wiring harness near the transmission. Squeeze the locking tab and separate the connectors for either sensor, if replacing the downstream oxygen sensors.

Install the oxygen sensor socket over the oxygen sensor so the pigtail extends through the opening in the side of the socket. Position the ratchet onto the socket and rotate the sensor counterclockwise to remove the sensor from the exhaust piping or exhaust manifold. Apply heat to the piping or manifold around the base of the oxygen sensor with the propane torch if the sensor is hard to loosen.

Remove the oxygen sensor socket and ratchet. Remove the oxygen sensor by hand.

Installation

Compare the old oxygen sensor to the new sensor. Pay special attention to the connector and length of the pigtail; the sensors should be identical. Inspect the threads of the new oxygen sensor and apply copper anti-seize to the threads if not pre-applied from the factory.

Thread the oxygen sensor into the exhaust piping or manifold by hand. Install the oxygen sensor socket over the oxygen sensor; directing the pigtail through the opening. Tighten the oxygen sensor to 28 foot-pounds with a torque wrench. Remove the oxygen sensor socket.

Connect the oxygen sensor pigtail to the wiring harness near the transmission, if either downstream oxygen sensor was replaced. Connect the upstream oxygen sensor pigtail to the engine wiring harness under the hood, if either upstream sensor was replaced.

Lift the front of the truck off the jack stands and remove the jack stands. Lower the truck to the ground. Shut the hood. Start the engine and clear any associated trouble codes.

Items you will need

  • Floor jack

  • Jack stands

  • Oxygen sensor socket

  • Ratchet

  • Propane torch

  • Copper anti-seize

  • Torque wrench