CEL went on, got KS and O2 codes
 

which O2 sensor is the (heater ??) sensor?

i don't have the code number cos i used an OBD2 app on my dad's laptop to pull it, it didn't give the code number, just what it means

so which O2 sensor is that? is it hard to replace?

the KS i know about already heh, dreading the day i have to replace it (oww my hands) :deezo:

get hte codes yourself

http://forums.maxima.org/showthread.php?t=104931

it didn't give you a PXXXX code?

Maximas have more than one heated o2 sensor. Did it say which one? Like front right, or front left?

Are you talking about the Front o2 (in front of the engine) and the rear o2 (behind the engine)? (not referring to the o2 that is by the cat)

When I got the exact same codes, I looked them up in the Haynes book and it said upstream and downstream. Are those the only two O2 sensors? I'm guessing so from the "front/back, left/right" ones you guys are talking about.

It seems to depend on the car, some people say cali and fed spec cars have different numbers of o2 sensors. But there's more than two sensors for either spec. And front/rear doesn't mean in front of the engine or behind it. It means in front of the cat converter or behind. There's two in front, lh and rh. rh is towards the firewall, lh is closest to the radiator.

thanks for the help, i stupidly reset the CEL when i was looking at the codes through the computer, and the light hasn't gone back on since.. that day, it was about 2deg F in the morning, so it might have been the extreme cold that triggered the o2 sensor to fail that time because it went on pretty much as soon as i turned the car on.

i was warming it up, so i didn't look at the dash as i turned the key, but when i came back into the car the light was on, so it didn't go on while driving.

my dad says that the sensor is probably fine, maybe not perfect, but working well enough to pass emissions and it was just the cold that made the sensor fail, or take too long to heat up so the CEL went on

i dunno, but now i have no way of checking which o2 sensor it was until the CEL goes back on heh.