My mechanic puled out the code P138 and also took the o2 sensor that it needs to be replaced.
Intsead of paying him $150 for a o2 sensor he was gonna get me I thought autozone was cheaper and I could try to replace it myself
Anyways, here's the pic of the senosr he took off my car:

(4 wires: 2 whites, 1 gray and 1 black)



and this is what autozone sells online:
Which one do I need to buy?

 

this info is in the stickies.
heres the link:
http://forums.maxima.org/showthread.php?t=559038

match up the code you got and BINGO.

 

thats a damn good sticky



i was gonna say "see sig link" but nsnrider beat me to it

you need "H02 S2-B1 White"...order it from daveb...you will get the correct one at a good price

 

how hard is it to replace it? i got the same code and O1039 as well. Would i need to have the car on a lift or is a jack and two jack stands sufficient?

also, is there any way to determine if you have a fed spec of cali spec car?

 

the first one you cut off half the harness of your old one, use crimps and attach the wires of the new o2 sensor to the harness of your old one

second one you just plug in and you are done

 

man soonerfan that a good diagram thats what ii was thinking when i was reading the post very useful diagram