Too lean bank 1? Its back!! HELP
 

Im not exactly sure if this is the correct location for this issue of mine. If I am in the wrong section, I do apologize.

Almost a year later of my "Its FIXED" post.... Its back. Code P0171 (Too lean bank 1). My last method of cleaning MAF sensor last year seemed to do the trick, but about 4 months ago it threw it again. Cleaned it again, cleared code and waited,... light returned. Let it be and it went off on its own after a few days. Scanned it, showed no codes. Few day later returned. About 3 weeks ago I cleared it again, and hasnt returned yet. But I know the code will fire again soon.

I need input here! Im not as mechanically inclined as I should be. I have heard that it could possibly be an o2 sensor. But there are 2 right? (upstream / downstream), Bad MAF? I really dont know here.

I have noticed that I've been flying through gas. Im not a lead-foot, the car doesnt even carry enough balls to actually be a tough guy with it. haha. But TOO LEAN? would that mean too much air, not enough fuel? or too much fuel, not enough air? Buddy of mine says he believes that it means too much air. ok but why the gas consumption? It almost makes sense ... correct me if Im wrong here.. If it were to be a bad MAF, MAF telling car that much air is entering(wrong reading), and to dump more fuel??? When in actuality, it not needed.

HELP ME HERE PLEASE! -- Sorry for the babble

Try this link to help diagnose your problem its very easy to understand OBD-II DTC: P0171 System Too Lean (Bank 1)

The o2 sensor that is on the rear exhaust manifold is the only one that measures for air/fuel ratio.

I would replace that (should be done every 50-75k miles), use only a high quality ACDelco replacement.

With that said, you could have a few problems, but that is common routine maintenance that should probably be done anyway.

I agree with Chibi, change the "upstream" O2 on the rear manifold. Stick with an AC Delco. I've heard Delphi is another good one (using it myself), but AC Delco, you're best best. BOSCH has been known to give issues.

Also, if you have not changed the plugs, it's probably time. Stay with AC Delco or NGK plugs (do NOT use BOSCH plugs, they suck). I've used AC Delco or Bosch wire sets (most off the shelf wire sets should be fine). I suggest plugs/wires just for good maintenance.

Make sure you have a clean air filter and try to re-clen the MAF. Check for vacuum leaks as well. A vac leak can cause/promote these issues.

A little maintenance and things should get back to good.

Thank you guys. I am going to check out some prices on o2 sensor. Only thing is Johnboyp92's link states its the downstream sensor where The_Maniac says its the upstream. Im sorry i am a noob with this..

And yes I actually am due up for another tune up pretty soon here. The last tune up, I used bosch plugs. This just gives me the extra nudge to hurry my ass up with it.

Our cars are difficult to talk about upstream and downstream because we only have 2 o2 sensors.

It's the only oxygen sensor before the catalytic converter, so it can properly read air fuel mix.

My personal experience with BOSCH plugs is that they either create a problem brand new out of box OR you are darn lucky if you go beyond 6 months without the beginnings of a mis-fire. I have stuck with AC Delco or NGK (fun fact about NGK, they make plugs for AC Delco, the Delco's I pulled from my wife's '05 Impala had NGK and AC Delco markings). I find I can typically get NGK platinum plugs shipped to my door from RockAuto a lot cheaper then buying them in the store. So far the '05 Impala, '02 Grand (and my recently sold '94 Grand Am) are running NGK Platinum plugs without a problem. Monte (at around 70,000 or less miles) still has the factory plugs.

Definitely make changing the plugs part of your plans!

Also, as Chibi mentioned, are cars (GM FWD v6's) are a little different then most. A lot of cars have 1 O2 sensor per exhaust manifold and MAYBE a 3rd after the Cat. We have 2. An upstream and downstream. For us, upstream is in the rear exhaust mani, before the cat, before the downpipe. Down stream is after the downpipe, after the cat.