How to Install an Oxygen Sensor in 4.3L Chevy Truck

There are commonly two oxygen sensors in the 4.3 liter engine exhaust system on a Chevy truck. One is the "upstream" sensor located on the driver's side Y-pipe near the manifold and the other "downstream" sensor which is located midway down the passenger side near the catalytic converter. Buying a direct-fit replacement sensor would be strongly advised. It's not much more expensive and it will save you time and effort struggling to rewire the universal after-market sensors.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Direct-fit oxygen sensor replacement
• 3/8-inch drive ratchet
• 3/8-inch drive oxygen sensor gasket
• Flathead screwdriver
• Safety glasses
• Creeper (optional)
• Portable propane torch
• Car ramps
• Wheel chock

How to Install an Oxygen Sensor in 4.3L Chevy Truck

1. Drive the Chevy truck up onto the car ramps on a level surface and place it in gear or park. Turn off the engine and apply the parking brake. Place a wheel chock behind one of the rear wheels.

2. Grab your tools, put on the safety glasses, and crawl underneath the truck on a creeper if you have one.

3. Locate the sensor you are changing. The front one is located on the driver's side up near the manifold and screwed into the Y-pipe. The rear one is located on the passenger side, down just before the catalytic converter.

4. Follow the oxygen sensor wire to the plug outlet. Unplug the sensor wire from the harness plug. Press in on the clip lock with the screwdriver and separate the plugs.

5. Place the oxygen sensor wire into the slot on the side of the oxygen sensor socket and place the ratchet on the end of the socket. Try to remove the oxygen sensor. If it is stubbornly stuck, remove the socket and ratchet and light the torch. Heat the pipe area around the sensor up, but do not heat the sensor as well. Once the pipe area is good and hot (cherry red) remove the sensor. If you had to use the torch to extract the sensor, allow the pipe area to cool down before proceeding.

6. Screw the new sensor in by hand. You will note that the new sensor has a light coating of anti-seize lubricant on it. Do not wipe this off. It will help for future removal and replacement. Tighten snugly with the ratchet and socket, but do not overtighten the sensor. You do not want to strip the threads of the sensor.

7. Plug the sensor back into the harness plug. Remove the tools and crawl out from under the truck.

8. Remove the wheel chock, release the parking brake, and drive it down off the ramps.

Tips & Warnings

• It may take several miles of normal operation to reset the "service engine soon" light that was triggered by the oxygen sensor to begin with. If after 100 miles or so, the light is still on, have the computer re-scanned.