Thread: P0171 Bank 1 Lean

Fuel pressure isn't the only reason for that code.

The V8 still uses only two o2 sensors so it could be a lean problem on either bank of the engine.

Meaning it could be a vacuum leak from a line, a bad intake gasket, throttle body gasket, intake tube issue or exhaust leak before the o2 sensor.

A live data scanner would let you watch fuel trims, then you could go around with brake cleaner or something to watch for a change in the trims.


Past that you really need a smoke/fog machine to check for leaks or rent/buy a fuel pressure tester to make sure fuel pressure is within spec. Sometimes you have to pay to fix stuff.........

thats a lean code, means a vac leak 99% of the time. o2 reads fuel trims picks up the lean condition, or os bad cause a bad reading and triggers the lean code. all these sensors talk to each other.

brake cleaner, or carb cleaner sprayed at the vac lines, sensors, tb gasket area lim area at idle can show a vac leak. brake fluid will make the idle bog down, carb cleaner will make it jump up. propane also works, will make idle jump up.

fuel pressure tester is a free rental at most parts stores, autozone/pepboys/advanced auto for sure. you leave a deposit and get the money back when you return it.

Do I bite my tongue or vent it out..........

Never did I say it was an o2 sensor. I said this vehicle has two o2 sensors and the those are labeled bank 1 sensor 1 and bank 2 sensor 1 in this vehicle. This engine is a V8 with only two o2 sensors, so both "sides" of the engine are being read by the front o2 sensor before the catalytic converter. It's an un-common setup because a standard V8 of this era has 4 oxygen sensors. Two for the drivers side and two for the passenger side.


So I listed other possible causes. Those being a vacuum leak and so on.


The intake tube should have been a no brainer, it's the TUBE going from the air box to the throttle body. They crack and split, leading to a leak that isn't suppose to be there.


The google would have told you what fuel trims are. Fuel trims are what the computer uses to see how the engines fueling is doing. High fuel trims leads to a lean code because there is more oxygen going past the sensor than the computer knows is right.

A live data scanner will show fuel trims and brake cleaner, carb cleaner etc etc is a fuel source. Spraying that stuff is adding fuel and that would in turn cause the fuel trims to change because fuel other than what is being sprayed into the engine via the fuel injectors is now being seen by the oxygen sensor in the exhaust. It helps pin point a possible cause for this code.



Everything I first typed out is in english, it's not my fault you don't understand what I am saying. Car repair and the lingo behind it is learned and I am not here to teach you this stuff. It's one reason shops and some mechanics make a lot of money.

Yeah I'm sure it's sounds like I'm being a dink here but if you had to ask those questions after my first post, you are better off just having someone else fix your cars for you. Unless you buckle up, research the **** out of your issue and educate yourself on how this code or other problem jive together. Even just using other forums/google etc etc to research possible cause for this code, they would have come up with super similar answers to what was already said.

100% not the way to get help around here. good luck to ya.

**** off dude. Yeah, i'm sick of your **** and i'm gonna say what everyone else is probably thinking. FFDP was a bigger man than me by kindly educating you even after you came back with an attitude. Look, no...no one knows everything. Thing is, you have acted like you do since you joined here, and people are annoyed by your cocky attitude. You say you wanna "make friends", yet you chastise people for not answering your questions the way YOU think they should. I basically know jack about engines before I joined this forum and asked for help. If it wasn't for the folks here, I'd still be trying to figure out misfires and leaks and how to tune and how to install a cam, etc etc. BUT, I didn't get all my information here. I researched the crap out of terminology, diagnostics, tuning etc on MANY different sites. It's out there.

Big thing you need to learn, no one is getting paid to help you. So stop acting like you DESERVE help. Be kind, be thankful and enjoy the adventure of fixing your own ****. Otherwise gtfo and throw money at a mechanic that probably doesn't give two ****s about your car.

Originally Posted by bandook

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Big thing you need to learn, no one is getting paid to help you. So stop acting like you DESERVE help. Be kind, be thankful and enjoy the adventure of fixing your own ****. Otherwise gtfo and throw money at a mechanic that probably doesn't give two ****s about your car.

this is same dude thats too cheap to spring for the $$ to get a carfax on a denali and asks people here to do it for him on their dime.

to answer the question- no. you need to pay a mechanic and probably for any future questions the answer will be take it to a shop.

Damn son, you got 30 college credits in English. I am beyond blown away by that.

Tubes and hoses are both mainly round shapes, maybe if you took some classes on that stuff we'd be okay.

it's getting salty in here!

and FWIW, FFDP's post was perfectly understandable.

Originally Posted by Hurricane87

.... and what I shouldn't have to spend it on is translating your post into English.

Is this serious or just being silly? His post WAS english and very basic at that. May I suggest that REGARDLESS of what the issue is or the code is just take it to a mechanic. You have no business opening your hood at this point.

So I've now read through the whole thread and came to the conclusion that OP is a frickin moron who refuses to be educated and cannot read basic automotive terms. Never should he/she EVER open their own hood and do anything. Drive straight to the shop. ALWAYS drive straight to a shop OP. What a disaster this thread turned out to be and all because the OP is a jack wagon with an attitude.

and so that this post makes sense to Hurricane....OP = Original Poster.....Hurricane, that is you. You are the OP I'm referring to

Originally Posted by Hurricane87

I asked NO ONE to "pay for a Carfax" for me, I asked for ways to figure out around the $15 (NOT $5). Someone else gave it to me, I did it, it worked, I thanked them. That's how it should work.

Despite the president we have, lies don't really help your argument. And if $15 is a trivial amount of money to you, why are you here?

heres your question,asshat:

Is there anyone, anywhere on this forum, who can look up vehicle history by the VIN?

do people just pull this out of their ass without paying to look up vins?

draggin the president into it? wtf,dude- go get help.

i dont have to answer why im here but i will.............................................. .....................

This seems like one giant sh!t show.

OP


Since you came here to learn...

Running lean on bank 1
P0171 Front Bank Lean
Codes P0171 Lean Bank One
P0171 - System Too Lean (Bank 1)


Im not saying that it will 100% for sure answer your questions, but at least then you will have a better understanding of what is going and the things that people recommend and why.