Check engine light came on in my wifes Sentra. Got codes scanned at Advance Auto and they came back P0171 System too Lean (Bank 1) and P0174 System too Lean (Bank 2) and pending code P0171 System too Lean (Bank 1). What would be the cause of this and how do I fix it? We have had the car not even a week and the light came on after I fueled it. Is this something I can fix or should I take it back to the dealer and get it fixed under the warrenty? Thanks for any help.

Could anyone tell me what this hose that is connected to the air box goes. It is the one right in front of the master cylinder. Sorry about not being able to get a close up the battaries in my camera was dying. The other end of is connected to the transmission.
http://i18.photobucket.com/albums/b150/bigdaddyII/XMInstall020.jpg

Hi, I have the same reading right now on my 2002 sentra I have change the upper sensor and noticed there are two more at the bottom of the manifold just before the cat converter. Its reading to lean !!!! please let me know what solved your problem so i can get mine solved thanks ... I got 90km om my vehicle..

I didnt change any sensors. I changed the air filter and cleaned the MAF and in the process found a vac. line that was unhooked and couldnt find where it went, so I plugged it up and the light reset itself after about 150 miles. I am still trying to find where that line plugs in to.

The simplest solution could be that there is a teeny bit of air coming in thru the gas cap. Just make sure the cap is tight after you fuel it, also make sure you dont leave the engine running while you put fuel in it, I was complaining about the same thing when my light came on and that was what I discovered.

if your problem comes back u might try cleaning your o2 sensors

The hose that you are describing is the transmission vent hose. It connects to the transmission on one end and to nothing on the other end, being a place to vent.

Both banks being lean would say that a sensor input to the ecm that effects both banks would be somewhere to look. Usually the Mass Aif Flow sensor will effect both banks.