Repair 7

How to Replace an Oxygen Sensor for 96 GMC

In 1996, GMC had 26 varieties of eight baseline models, all of which were pickup trucks, vans or SUVs. These models ranged in size from a quarter-ton to 1 ton, and though they had different motors, most of them had two oxygen sensors that screwed into the exhaust system and monitored the ratio of oxygen to burning fuel in the exhaust. The one closest to the motor (on the drivers side exhaust pipe near the manifold) is referred to as the "upstream" oxygen sensor, and the one near the catalytic converter is the "downstream" oxygen sensor. Buy a quality direct-fit after-market oxygen sensor and put it in yourself to save some money on labor charges.

Instructions

1

Drive the GMC onto the car ramps carefully until the front wheels center in the top pits. Turn off the engine, place the GMC in park or gear, and apply the parking brake. Place a wheel chock behind one of the rear tires.

2

Put on the safety glasses and grab all the remaining gear and crawl under the GMC on a creeper. Locate the oxygen sensor youre replacing by following the exhaust system from the front left Y-pipe near the manifold to the catalytic converter.

3

Follow the oxygen-sensor wire to the plug about 8 inches away and separate the plug using the flathead screwdriver to press in on the plastic clip lock.

4

Put the oxygen-sensor socket onto the ratchet and place the oxygen-sensor wire in through the slot of the socket on the side. Remove the oxygen sensor. If the sensor is stubbornly stuck, remove the socket and ratchet and light the hand torch. Heat the area of the exhaust pipe that surrounds the sensor to expand the metal and try again with the ratchet and socket until youre successful. If you had to use the torch, allow the exhaust pipe to cool down before you proceed.

5

Screw the new oxygen sensor into the porthole in the exhaust pipe. Most quality direct-fit sensors should have a light coat of anti-seize lubricant on the threads. Do not wipe that off, as it will make future removal and replacement procedures helpful. Tighten the sensor with the ratchet and socket, but be careful not to overtighten and strip the threads of the new sensor.

6

Reconnect the sensor wires at the plug connection. They will only fit one way.

7

Gather the tools and crawl out from under the GMC. Remove the wheel chock and lower the GMC.