The oxygen sensor on your Saturn SL monitors the Saturn's exhaust. It sends information about the pollutants in the exhaust so that the SL's computer, called an ECU, can make adjustments to the air/fuel ratio. These adjustments help to optimize fuel economy and horsepower while reducing emissions. When your SL's oxygen sensor fails, your fuel consumption will increase noticeably, and your general engine performance will decrease.
Raise the Saturn SL onto jack stands. To do this, jack up on the front jack point behind the radiator and place a jack stand under each of the jack stand points under the driver and passenger side doors. These points are pinch welds and are part of the unibody construction of the SL. Then, lower the vehicle onto the stands.
Climb under the vehicle and disconnect the lead wires from the oxygen sensor which is located near the catalytic converter--the egg-shaped component inline with the exhaust) Depending on your model year, you may have one or two sensors.
Unbolt the oxygen sensor or sensors using an O2 sensor socket and socket wrench.
Remove the oxygen sensor from the exhaust and insert a new oxygen sensor. Thread and tighten the new sensor using an O2 sensor socket and socket wrench.
Reconnect the electrical leads to the sensor and lower the Saturn to the ground.
