How do you replace 2001 Subaru Outback oxygen sensor?

the oxygen sensor is located between the fist and second muffler. you will need to disconnect the sensor and it will then unscrew out of the exhaust pipe. I just did this on my H6 and I also needed to replace the air mix sensors on each side of the motor. they look just like oxy sensors and my need to be replaced as well. they are located on either side of the headers. the best way to get at them is from under the hood. you will also have to disconnect these sensors from the top and then unscrew them from the headers on each side.