What is the procedure for replacing the O2 sensor on a 2001 Nissan Maxima?

How are you, My name is Matthew from Scottsdale, I too have a 2001 maxima and I love it. the service engine light came on a few weeks ago and I,m pretty sure it is the sensor. First off there are 3 of them. they look very easy to replace. If you pop the hood and look at the gap between the mainfold and the radiator you will see 3 wires one is blue, red, white. (if it is the same as my maxima) Each wire clips into this plastic holder (should be covered with electrical tape). The blue wire runs to the left into the mid part of the manifold about 8 inches from where it started. The other 2 (red and white) runs down the the bootm of the engine (yikes!!) But if you follow them down to the bottom of the car you will see that they are not really hard to get to. With a little bit of diligence and patients I think it is really possible. The one question I have is which sensor is the problem Blue White of Red? I work at Sears at night and I am going to ask if they can figure out which on it is and see if I can't replace it myself. No need to change a sensor if it isn't needed. But the question now is if it will still in fact shut off that Service engine soon light. Well lets take care of one problem at a time. I'm going to find out if they can't look at my car tomorrow. Until then safe driving fellow 2001 Maxima owner! Please if anyone has better suggestion please I'm all years.