Well i got an oxygen sensor code but what i want to know is how do i know whitch sensor to replace? i dont wana buy all 3 of them at 50 dollars each...

p0140 is the code for anyone wondering.

 

http://forums.maxima.org/5955544-post2.html
I would just replace one bank (two sensors) at a time.

 

That code cross-references to an undefined code.

P0140 = 0512

0512 is undefined.

You sure the codes is correct?

You've apparently pulled the code with a reader, yes?

 

second one on y pipe before converter, iirc. I'll double check when i get off work

Haynes repair manual FTW!

 

yeah im positive it's p0140
i also got a p0325 a knock sensor code if that helps.. lol

 

uh, that does help. when you get knock and O2, the O2 usually goes away once you fix the knock sensor. Go to ebay and get an OEM one for like $40

 

P0140 indicates the rear 02 sensor. If you have anywhere near 100k miles, replace your 02 sensors. The regained mpg and performace is well worth it. They are one of the few parts I replace without testing. They'll get real lazy before quiting, and it's a gradual process you wont really notice. The rear 02 sensor has notihng to do with performance/mpg though. A fault from it usually indicates your front 02 sensors are starting to get tired and cant tell the ecm what the conditions are and adjust accordingly quick enough. Definately test the KS before replacing it as it is a part that either works, or doesnt. There is no gray area for it's operation unless you over/under tq. the bolt that holds it to the engine.

 

how do i check if the KS is working or not? i alraedy ordered one off ebay lol

they have 35 dollars with shipping for oxygen sensors are they all the same? should i just get 3 of em.

 

Look a few threads down or search. It was just talked about (how to test it.) The only difference in 02 sensors is if it has the original wiring harness plug to attatch to your car, or if it's a universal splice in. For $35, it's got to be universal. It's not a big deal, just cut the plug off your old 02 sensor and splice/weld to the new 02 sensor wiring to it. As far as brand, they are probably all about the same. I would stay away from the Ebay "no name" one's though. They might be just as good, but I wouldn't chance it myself. I used http://www.oxygensensors.com/ when I got mine. They had the OEM style harness plug. Can't remember what I paid though.