Heated oxygen sensors should be checked or replaced every 60,000 miles, while unheated oxygen sensors should be checked or replaced every 30,000 miles

It is best to replace O2 sensors in pairs. Because, replacing one sensor will cause the ECU to set a code for the other sensors. This is because the new sensor switching activity is much faster than that of the older aged sensors

If you are using an open end wrench, try an O2 socket. If this fails, try a long ratchet or breaker bar in conjunction with your socket to generate more torque. After the sensor is removed, be sure to use a thread cleaner to clean up the bung threads

1 Oxygen sensor circuit failure

2 The mixture is too rich

3 The mixture is too lean

4 The three-way catalytic converter is damaged or fails

5 Damaged ECM