How to Install O2 Oxygen Sensors on a Lexus IS 300


Park your car in a safe place with a level surface and plenty of room for you to work around the vehicle.


Start the engine and let it reach operating temperature; then turn the ignition Off.


Open the hood and disconnect the black, negative battery cable.


Locate the oxygen sensor following the exhaust manifold down the exhaust pipe. You should see the sensor threaded into the pipe just before it connects to the catalytic converter. On some Lexus models, it is necessary to raise the vehicle to locate and reach the sensors. Raise the left side of the vehicle using a floor jack and place a jack stand near the front tire; if you are replacing both oxygen sensors, raise the back of the car and place another jack stand near the rear tire.


Unplug the oxygen sensor's electrical connector. Push the lock tab and separate the connector from the vehicle harness. Be very careful and keep your hands and body parts away from hot exhaust system components. On some Lexus models, you may need to remove the passenger seat and lift the carpeting in order to find and unplug the sensor's connector.


Remove the sensor using a box wrench or ratchet and oxygen sensor socket. If the sensor seems hard to remove, apply penetrating oil around the sensor mounting base according to the manufacturer instructions. On some Lexus models, the sensor attaches to the exhaust pipe with a flange and two bolts or nuts; use a wrench or ratchet and socket to remove the bolts or nuts.


Apply anti-seize compound to the new sensor's threads if you are installing a screw-in type sensor. Make sure not to touch the tip of the sensor with anti-seize compound. Start the sensor into the exhaust pipe by hand first; then tighten the sensor using the box wrench or ratchet and oxygen sensor socket. If you are installing a flange type sensor, install a new gasket and set the flange and sensor in place. Thread in the flange mounting nuts or bolts and tighten with a wrench or ratchet and socket.


Plug the sensor's electrical connector. If you are replacing more than one sensor, locate the second unit at the other end of the catalytic converter and replace it following Steps 5 through 8; then lower the vehicle and connect the black, negative battery cable.

Tips and Warnings

  • Consult your owner's manual or vehicle service manual to identify or locate components. You can buy one at most auto parts stores or consult one for free at most public libraries.
  • It only takes a few minutes for the exhaust system and related components in your vehicle to reach very high temperatures. Whenever working under these conditions on your car, use caution to avoid skin burns and other injuries.
  • Installing new oxygen (O2S) sensors on your Lexus IS 300 is a simple process if you take the necessary precautions. The exhaust system, where the oxygen sensors are located, may heat up to 1,500 degrees F in 3 minutes or less. However, you can safely replace one or more oxygen sensors in your vehicle in a matter of minutes following these simple steps.