O2 sensor or what?
 

i got a 96 GT. CEL is on and car runs bad at idle. scanned it with scanner and it says O2 sensor lean sensor 1 bank 2 now is this a bad sensor(in which case how do i know which one it is) or is my car actully running lean? friend told me it could be injectors(which means the cars gonna sit till i take it to get the new PI heads im getting for christmas). anyway any help would be awesome.
Also any one know a good spot to get heads installed and a dyno tune in south jersey let me know :)
any suggestions on what heads to get would be appreciated. thanks

normally you'll see that with a:

vacuum leak
bad front o2 sensor
exhaust manifold gasket leak ahead of the front o2 sensors.

I'm betting you've been fiddling under the hood and have a vacuum leak. Did you not put the dipstick all the way back in or leave the oil cap loose?

CEL
 

My CEL came on a couple of weeks ago after I installed a new CAI. It got contaminated so I disconnected the battery, cleaned the MAF with a lot of MAF cleaner, reinstalled the MAF, reconnected the battery and the light was gone. It only cost me $7. Worth a try!

If its both its more then likely a leak somewhere.

thanks for the ideas guys.
i havent been under the hood for about 6 months. other than oil change 2 months ago. i looked at all vacumme lines they look good. dip stick and oil cap are good. also scanner only said it was one O2 sensor.
i do however think that i got an exaust leak(new funny sound) but im not sure how to check it.(start the car and put you hand down around the manifold to feel for air flow? without burning it off? lol)
anyway i figure if i change the front o2(thanks SPIKEAFRICA) and i still got a problem, i know its a leak.
i will post when the new O2 is in and let you guys know if its fixed.
thanks again

oh and hey if i just leave a buddies oil cap loose will it throw a CEL with doing damage? cause i really want to mess with some of my friends. yep im an a-hole :)

check your PCV Valve hose...i had exact same engine codes, and I changed both my front sensors and it didn't solve the problem. mine turned out to be a bad PCV Valve hose, and a clamp on the airbox was loose.

the upstream 02 sensor lack of oxygen code, means your problem is before going into the upstreams 02 sensors.

check Airbox clamps, PCV Valve, vacuum hoses, PCV Valve hose, IAC Sensor gasket.

check for intake manifold gasket leaks as well. if all that doesn't work, then replace the sensor.

thanks for the help guys i replaced my front passenger O2 and it seemed fine, but then i got new codes and a CEL. now it says "manufactures fuel air controll" . Minike(lol i think thats how its spelled) put in my new mid pipe (BBK with highflow cats), and they said to bring the car back in this wendsday. i checked all the hoses and the PCV valve everything looks good. ill post when its fixed thanks again.:D