1996 Toyota 4Runner Replace O2 Sensor

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The 1996 Toyota 4Runner has two oxygen sensors located in the vehicle's exhaust pipe. They detect the presence of oxygen in the exhaust gas and send the information to the truck's Electronic Control Module (ECM). The ECM adjusts the fuel/air mixture based on this information for optimum performance. A bad oxygen sensor is one thing, among many, that will cause the check engine light to come on.

Tools Used[edit]

2 new oxygen sensors

Replace O2 Sensor[edit]

  • Start the vehicle and let it reach operating temperature. This allows the exhaust pipe to expand, making it easier to remove the sensors. Turn off the vehicle and disconnect the negative battery cable.
  • Raise the vehicle with a jack and support it using jack stands. This step is not critical, but it will give you more room to work while under the 4Runner.
  • Move underneath the vehicle, approximately in the midline. Locate the catalytic converter, which is the large part of the exhaust pipe. Approximately 6 inches in front of the catalytic converter, you will see something protruding upward from the exhaust pipe with a cable attached to it. That is the forward oxygen sensor.
  • Use a wrench to disconnect the electrical connector at the connection point, about 8 inches from the sensor. Do not disconnect the cable from the sensor itself. Use the wrench remove the two oxygen sensor bolts and remove the sensor from the exhaust pipe.
  • Follow the catalytic converter about 6 inches towards the rear of the vehicle. You will see the aft oxygen sensor also protruding upward from the exhaust pipe. Follow the procedure described in Step 4 to disconnect and remove it.
  • Insert the new forward and aft oxygen sensors. Replace and tighten their bolts. Connect their wire leads to the connection points
  • Lower the vehicle and reconnect the negative battery cable. Test-drive the vehicle to ensure the check engine light remains off.

Tips & Warnings[edit]

  • The exhaust pipe will be very hot. This is necessary to be able to remove the sensors. Wear long sleeves and be careful to avoid the pipe.
  • If you raise the vehicle, make sure it is securely supported with jack stands before you get underneath.