Does anyone know the best way to change o2 sensor bank 1 sensor 2 ? on a 99 es 300 , how many post cat sensors are there?

 

The best way to access Bank 1 Sensor 2 (post-cat) is to raise the rear end of your car with a floor jack. From there you'll easily see the sensor located along the exhaust pipe after the catalytic converter. Unplug the sensor with a 22mm or 7/8" wrench, and disconnect the electrical connector associated with the sensor. Install the new sensor, and apply a torque of 33 ft-lbs. That is the DIY version of replacing an O2 sensor

 

I did it:

1. remove driver's seat ( I took it out of the car for clear space. Or you can just move it to the back. only 4 nuts/bolts. Disconnect two electirc plugs under the seat before removing seat )

2. pull floor carpet on the left side of center console( left side of the center box). Find the O2 sensor connector and disconnect it. The wire goes into the car through a hole on the left side of the console and end up right under the driver's seat.

3. push the connector end out of the car. Use special socket ( I borrowed one from autozone ) to turn the O2 sensor off.

4. installation is the reverse of the above: turn a new O2 sensor in with the connector end loose. This way you will not screw the wires. then push the connector end into the car, plug it on to the harness connector. reinstall the driver's seat.