P0171 Trouble Code: System Too Lean Bank 1 (The Most Common Causes)

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[growrich]

You provide so much value for free, it’s insane. Thank you man!

[factotumted]

Great information. Thanks!! The cause on my 2004 Honda CR-V was a bad intake manifold gasket!!! Took forever to diagnosis it.

[sooflex]

It’s way to many things that could be wrong

[tiffanycox]

P0171 Code : Lean code, too much air.

Air Fuel Ratio : 14.7 Air = 1 Fuel

14.7 parts of air to 1 part of fuel.

1. Vacuum Leak :
2. MAF Sensor
3. Fuel Issues : Fuel Pump, Fuel Filter, Fuel Injectors, Fuel Rail Pressure Sensor, Restricted Fuel Line
4. Exhaust Leak
5. Oxygen Sensor
6. ECM

[PlanB-]

Excellent info 👏🎉
Thank you👍
Greetings from Egypt 🕊️🇪🇬🕊️

[omnizen]

Vehicle in question is a 2003 VW Passat GLX, 6 cylinder, automatic transmission, front wheel drive. This vehicle has always had a seemingly high idle speed, even when it comes back from service at the Dealership.

I am getting P0171 and P0174 for the same "too lean" condition on both right and left banks. If idle speed was set too low (on last service at an auto repair center), what do you think the chances are this might be the cause?

RANDOM QUESTIONS:
Does the ECM control the idle speed and the mechanic cannot adjust it?

Could a low idle speed cause the ECM to calculate and inject the wrong amount of gas because the ECM is programmed to function as though the idle speed is set correctly?

If the ECM knows the mix is lean, why does the ECM not adjust the mix accordingly by increasing the fuel injection interval?

Could it be the idle speed has been running low . . . BECAUSE OF A VACUUM LEAK, . . . and the engine therefore has insufficient power to maintain the correct idle speed because of the weak fuel mix?

[hakeemboyd]

Getting a Chevy sonic for a cheap price and after scanning it I saw those popped up but contemplating if to still go ahead or save my money

[bradh]

I'm getting P0316 P0171 and P0303. Does this combination rule out some of the possible problems?

[JGG]

P0171 ONLY on my 2020 Ford F150. I have only 26, 000 miles on it. I saw your possible reasons. I have extended warranty but my dealership doesn't do 3rd party warranties.
Now what would you recommend sir?
EDIT:
I bought the truck brand new. This shouldn't happen so soon should it?
Edit:
Took it to a dealership. They replaced purge valve. But they would NOT guarantee that was the problem. I paid for diagnosis, parts and labor.
If the code reappears, they told me to bring it back. And for what? Only to charge me again and possibly again and again?
Thats just not right.😠

[gbowers]

I’ve got this code on my 2006 Camry with 280k miles and I’ve noticed I also have a 16% absolute throttle position during idle when looking at the live data on my BlueDriver which I’m pretty sure is way too high. Would this most likely indicate it’s the throttle position sensor that needs replaced? The absolute throttle position percentage when the code last got tripped on the freeze frame data was 30.6%.

[DaveSam]

I had both codes right after I ran out of fuel while driving
Engine was rattling on first start then goes well but the engine still stumble at 4000rpm rev

[marcgabel]

Hi, I have had that code for over a year. It has cleared itself. Engine light goes off. Or I clear it. Last week It started running okay when cold but when hot looses power. In that year I have been driving and testing. Has new fuel pump and filter. Ideas?

[wolleyreikivalley]

what if you get this right after getting gas on a super hot day (100°) and you clear it and it doesn’t come back

[partyatsams]

my car is ticking on warm ups but not when hot can u help with some info so i can take care of it

[danemaddalena]

I have a 01 Ford expedition I just want a new computer n wiring harness or just get a carburetor 302

[taco]

I know nothing about pop1 code 171, I asked my neighbor and he said I need a vacuum brake booster, but he also said he didn't know if that 02 is damaged, I'm a military wife I took it to three mechanic and each one said something different with outrageous prices, I trust my neighbor advice he said I should only get the vacuum brake booster to see if that takes care of the problem, what do u think 🤔

[Hakeem]

How much you think that they will charge me to get it fixed

[EkiPisanwanitkul]

Anyone getting this code only and car randomly shuts off

[matijamolan]

What when code says sistem too fat? Any advice?

[nebs]

My car is hesitating like it’s not getting enough air or gas