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Discussion Starter #1
So my check engine light came on, got a code of P0171 lean in bank 1. My car has been idling rough and exhaust doesn't smell right. The print out Autozone gave me after the scan said "Clean fuel injectors" is that accurate?

From what I've read online it could be a few things. I cleaned the MAF sensor which didn't help so I planned on changing the front driver's side O2 sensor, I see it but not sure how to get to it. I bought a sensor socket but there is no way i can get to it with that. Should i just us an open ended wrench? Is there an easier way to reach it?
 

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Better get a monkey wrench on that thing. A lot of them came cross-threaded from the factory. Mine were a bitch to get out.

That's not the issue though. May just be able to run some injector cleaner through the tank and be good to go.
 

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This is what I came across.

Causes

A code P0171 may mean that one or more of the following has happened: The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry. There could be a vacuum leak downstream of the MAF sensor Possible cracked vacuum or PCV line/connection Faulty or stuck open PCV valve Failed or faulty oxygen sensor (bank 1, sensor 1) Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!) Exhaust leak between engine and first oxygen sensor

Possible Solutions

A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include: Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling Inspect all vacuum and PCV hoses, replace/repair as required Inspect all hoses and connections in the air intake system Inspect and/or test the intake manifold gaskets for leakage Check for a dirty fuel filter and proper fuel pressure Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool If you have access, you may want to run a smoke test
 

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Try fuel injector cleaner first. It's cheap and easy.

An open end wrench will likely round out the oxygen sensor, so be careful. If you can't fit an oxygen sensor socket on it because of the angle, perhaps try loosening the exhaust clamps and rotating the midpipe? Be sure to spray PB blaster on the o2 sensor a couple of times before you attempt to loosen it. Also, run the car until the exhaust gets hot because heat will expand the oxygen sensor bung and that will help tremendously. Good luck.
 

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No joke the original O2s are tough and I ditches the socket quick and actually had to come back to em a 2nd time. Spray the blaster over the course of a few days so that you go through some heat cycles. They finally broke loose with a couple monkey wrenches looped together and laying in awkward positions to where your not on the hot pipes and could get a decent grip on the sensor.
 

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You said you cleaned the MAF but it didn't help.

Did you turn the CEL off after cleaning the MAF and it came back on? The CEL needs a few driving cycles where it doesn't see a fault before it will clear itself. The light won't go off immediately on it's own once the issue is resolved.

Any mods to the car?
 

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Discussion Starter #7
The first thing I did was use fuel injector cleaner and the light did actually turn off with in a couple minutes of driving and turned back on the next day. After cleaning the MAF I noticed better throttle response but still having the same issues, I didn't clear the light, it hasn't turned off on its own and it has been about a week.

The only mods are volant intake and SLP catback and all hoses seem to be fine.
I am going to spray with PB blaster the next few days like suggested and take a crack at replacing sensor this weekend.

Most importantly, is driving the car while running lean going to cause more problems? This is my daily driver and have been using it to get to work with this issue the past two weeks. It seems to drive fine on the highway but idles rough at a stand still, the rough idle does come and go as well.
 

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How many miles?

If it's actually running lean, then yes you can do damage driving it. How much damage all depends on how lean it's actually running. That said, I'd simply take it easy and avoid going WOT till you resolve it.

As far as the upstream sensor, prepare yourself for a battle removing it. You may get lucky, but if not, just carefully go back and forth with the sensor. If it strips, you should be prepared to have something to chase the threads in the mid pipe also as the O2 sensor threads is what will rip off. Trying to thread a new one in there could wind up being a bitch if you have threads from the sensor still in there.

Good luck.
 

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To get my front O2s off I cut part of the connector tabs off and used the boxed end of the wrench. I can still use the O2 sensor. Replacing the O2 should be the last resort.
 

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I took my old headers and midpipes off of the car and this one O2 sensor took me 3 days to remove. I started with an O2 sensor socket on a pneumatic impact drill and immediately rounded it off. I spent the next couple of days using a dremel to square it off again and finally was able to get a 20mm open end wrench on it using with the persuasion of a hammer. I then used the midpipe as a breaker bar and finally got the damn thing out.

Definitely use PB blaster and heat liberally before you give it a go, because if you round it off you're in for a trip. Also pick up an O2 sensor thread chaser and anti-seize for your replacement sensor.
 

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You would of had it off a long time ago if you would of used a pipe wrench after you messed it up.works everytime!
 

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Discussion Starter #12
I tried again today to get the front drivers side sensor off and it just wouldn't budge. I sprayed it once or twice a day with knocker Loose for the past week, jacked it up as high as I could and was able to get the sensor socket on but the little room it left me was only enough for the play in the socket. I tried a 22mm open ended wrench but with how the sensor is threaded on I couldn't even get it on. Maybe with an offset wrench but couldn't find a 22mm.

The car has 62,000 miles, I needed a new battery so I replaced that before trying the sensor. I let it sit for 2 hours with no battery then put in new one but ran the same and the light came back on. At idle it was reading around 1.2 -2.2 GPH. Since I couldn't remove the sensor I disconnected it and let it idle and drove around the block. The idle has dropped to normal range .8-1.2 and it drives better so i'm fairly certain it is the sensor that is the problem.
 

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if you still have the stock mids, drop 'em, put in jba mids, and take your old mids to the wrecker to get some cash for the cats.

new o2's screw in great into new mids. :thumbs:
 

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I couldn't get my 02s out without the socket thingy. I sprayed a whole can of pb blaster on them, used all my strength and it wouldn't budge. Maybe i'm just a girly man.
 

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Another idea is to re-torque the bolts on the manifold on the driver side. I had the same code but was Lean Bank 2. Found 2 of my manifold bolts were loose, I couldn't even hear and exhaust leak but the PCM was able to read it. Re-torqued them and the codes gone.

Told my wife it was a temporary fix and that I needed Kooks headers and mids to totally resolve the issue ;)
 

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I got a good story, had problems just as the vehicle was coming up to temp, at WOT she would sputter, fall flat on her face, spew raw gas out the pipes, and the CEL would flash. She'd warm up, and all was fine.
Changed the spark plugs and O2 sensors and haven't had the troubles since.

The O2 sensors were screwed into a set of SLP long tubes that had been part of the SLP Bobcat 455 performance package that was installed by the dealer. The sensor was easy enough to get at but had a bitch of a time getting one of them out. Had borrowed a buddies O2 socket and thread chaser; destroyed both and had to buy him new ones when all was done. There was weld splatter on the bung threads from the bung being welded to the pipe. Stripped the O2 sensor royally as it came out, cross threaded it to where it didn't want to budge. Once finally out, I cleaned the threads off the bung the best I could and screwed the new sensor in. I hope I never have to remove it! Probably just buy a new set of headers...
 

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Offset o2 sensor removal tool + breaker bar. One of the best tools I've ever bought. You can get them pretty much anywhere.
Added to my Amazon wish list should the time ever come!
 

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As long as the O2 isn't cross threaded, I've always been able to put a 7/8 wrench on them and give the wrench a real good smack with a hammer and they will break free. Can usually hand spin them out after that. The couple of cars I've worked on with the cross threaded O2s are a nightmare. They look exactly like the pic in the post above mine. Threads are gone and usually end up rounding corners off of the O2. If that happens, you need to try and get a tap to clean out the O2 bung before you thread the new one in.
 
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