How to Change an Oxygen Sensor on Gmc Cars

by Contributing Writer; Updated June 12, 2017

The Gmc car oxygen sensor is a critical component for your vehicle. The oxygen sensor monitors the amount of unburned oxygen that is in the exhaust as the exhaust exits the engine. This is an important process for the vehicle as it controls the fuel mixture and regulates the Gmc car engine performance and emissions. When the Gmc car oxygen sensor begins to fail or is completely bad, the vehicle's drivability will be affected and you will notice increased fuel consumption.

Under The Hood:

 How to Change an Oxygen Sensor on a 2004 GMC Truck

Position a jack under the front suspension of the truck and raise it off the ground. Position a set of jack stands under the front suspension or frame rails to support the truck, then lower the jack and remove it from under the truck.

Locate the O2 sensor you intend to change. If it is the upstream sensor, find it under the engine in the down tube that runs from the exhaust manifold to the catalytic converter. If it is a downstream sensor, it is in the exhaust pipe just in front of the catalytic converter. On dual exhaust trucks, there are two downstream sensors on in each pipe.

Locate the wiring harness pigtail coming out of the top of the O2 sensor. Follow the wires up to the electrical connector at the vehicle wiring harness. Disconnect the connector by pushing down the locking tab on the connector and pulling the two halves of the connector apart.

Place an O2 sensor socket on the O2 sensor in the exhaust pipe. If you do not have one, you can buy an O2 sensor socket at most auto parts stores. Using a 3/8-inch drive ratchet, turn the socket counterclockwise, loosening the sensor. Lift the old sensor out of the pipe and discard it.

Thread the new O2 sensor into the hole in the pipe by hand to avoid stripping or cross threading fit. Tighten it with the O2 sensor socket and ratchet, then run the wiring harness pigtail up to the connector on the truck. Push the connector on the O2 sensor into the wiring harness connector, making sure the locking tab engages. Repeat this process for each O2 sensor that you need to change.

Position your jack under the front of the truck again and lift the truck off the jack stands. Remove the stands from under the truck and carefully lower the truck to the ground.

Items you will need

  • Jack

  • Jack stands

  • O2 sensor socket

  • 3/8-inch drive ratchet

 How to Change an Oxygen Sensor in a GMC Envoy

Turn the Envoy’s engine off and allow the vehicle to cool for 10 minutes. The oxygen sensor is easiest to replace while the engine is still warm.

Open the hood of the Envoy using the hood-release lever in the vehicle. Locate the oxygen sensor on the exhaust manifold. If needed, refer to the Envoy owner’s manual for exact location and a picture.

Loosen and remove the oxygen sensor by using a 22 mm socket wrench or a special oxygen sensor socket. Twist the socket wrench counterclockwise until the sensor is loose enough to remove.

Connect the new oxygen sensor by plugging it into the connector on the exhaust manifold. Close the hood of your Envoy and pull up to ensure the hood latches shut.

Items you will need

  • Wrench

  • Oxygen sensor socket or 22 mm socket

  • Owner’s manual

  • New oxygen sensor

 How to Replace the Oxygen Sensor on a GMC Yukon

Raise the front end of your GMC Yukon using a jack. Place a set of jack stands beneath the front of the truck to secure it. Remove the jack.

Remove the retaining clip from the wiring harness connected to the oxygen sensor by pulling it up to release it. Remove the wiring harness from the sensor. The GMC Yukon uses a wiring harness that pulls free by hand, so carefully pull it upward away from the sensor.

Remove the oxygen sensor using an oxygen sensor socket and ratchet. Check the thread area on the truck and wipe it with a clean rag if needed to clear any debris.

Insert the new oxygen sensor using the oxygen sensor socket and ratchet. It may be easier to thread it in by hand so that you don't cross-thread the sensor. Torque the sensor to 31 foot-pounds with a torque wrench.

Raise the truck with the jack. Remove the jack stands. Lower the truck to the ground.

Items you will need

  • Jack

  • Jack stands

  • Oxygen sensor socket

  • Ratchet

  • Torque wrench

 How to Replace an Oxygen Sensor on a 2000 GMC Sonoma

Park the GMC Sonoma on a flat paved or concrete surface and apply the parking brake.

Place a wheel chock behind one of the rear tires.

Lift the left front quarter of the truck with a floor jack and place a jack stand under the front left frame rail. Repeat this for the right side to elevate the front axle of the truck.

Put on the safety glasses. Grab the tools and new sensor. Crawl under the truck on a creeper if you have one.

Locate the sensor you need to replace. The upstream is on the left-hand side (driver's side) of the front exhaust Y-pipe near the manifold connection. The downstream sensor is near the catalytic converter.

Spray the threads of the sensor with the spray lubricant and allow it to soak in a little.

Unplug the wire harness from the sensor. Use the screwdriver to press in the locking clip on the plug and separate it. You may have to pry out the plastic push pin to make it easier, but you can use the screwdriver to do that, too.

Place the wire of the sensor through the hole of the 22 millimeter box end wrench and attempt to loosen the sensor turning it counterclockwise. A lot of times, the sensor will loosen when applying the proper amount of strength and tenacity. However, you may need to heat the pipe area where the sensor threads into with the hand torch to expand the metal around the sensor threads. If you have to do this allow it to cool down before reinserting the new sensor.

Apply a light coat of anti-seize lubricant to the threads of the new oxygen sensor. Be careful not to get any on the sensor head. Many quality sensors may very well already have some anti-seize lubricant coated lightly on the threads.

Screw the sensor into the pipe by hand at first and tighten with the wrench. You'll have to feed the wire of the sensor through the box end of the wrench again. Tighten securely, but realize there's only 4 or 5 threads on the sensor so over-tightening it can easily strip out the threads and damage the sensor.

Plug the wire back into the harness and the push pin back into the pre-drilled hole.

Collect all the tools and old sensor from under the truck and lower it down.

Items you will need

  • Floor jack

  • 2 jack stands

  • Wheel chock

  • Creeper (optional)

  • 22 millimeter box end wrench

  • Flathead screwdriver

  • Spray lubricant (WD-40)

  • Anti-seize lubricant (optional)

  • Safety glasses

  • Portable hand torch (optional)