All of a sudden, you notice that you are getting lower gas mileage than before. Most likely, this is a simple case of a bad O2 sensor because the first sign of this problem is poor gas mileage. Learn how to remedy the problem and replace the sensor.
Use a generic code reader to be sure you need to replace the O2 sensor. Hook it up according to the directions.
Locate the O2 sensor under the car. If it is easy to reach, proceed to turn and remove the sensor. More often than not, you must get a specially made oxygen sensor socket. If so, use this socket to replace the sensor.
See whether the sensor comes out easily. If it does not, use freeze spray to help loosen it.
Pass the new harness and sensor into place where your removed the other, using the manufacturer's instructions. Check the seal to be sure dirt and water cannot get in easily. Tuck the excess wiring out of sight.
