Engine Fault Code P0171 - System Too Lean Bank 1! [Symptoms, Causes, and Fixes]

Getting engine fault code P0171 - System Too Lean Bank 1? Unraveling the mysteries behind engine codes can be daunting. One such code, P0171, often confounds drivers and DIY mechanics alike. What does it mean, and how can you resolve it? Dive into this comprehensive guide on the P0171 engine fault code, where we breakdown its meaning, causes, symptoms, and the steps to diagnose and remedy the issue. Understanding P0171 is essential for maintaining optimal engine performance and ensuring the longevity of your vehicle. Whether you're a seasoned mechanic or just a curious car owner, this guide offers practical insights and actionable steps to address the P0171 code.
If you would like to read up on this issue more, we wrote an article over on our TuningPro website: tuningpro.co/p0171-code-sympt...
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00:16 - Fault Code P0171 Meaning
00:45 - What Does Bank 1 Mean on P0171?
01:57 - Most Common Causes of Engine Code P0171
02:48 - Symptoms of Engine Fault Code P0171
03:22 - Can I Drive with a P0171 Engine Code?
05:03 - How to Diagnose Engine Fault Code P0171
08:06 - Cost of Fixing P0171 Engine Code

[@gavinw6532]

I just got this code on my 2015 Mazda 6 touring. Great information thank you.

[@8020Media]

G - Thanks for the feedback! We hope it helps.

[@JCrew4uthatguntalk]

Excellent information thank you!!!

[@8020Media]

Glad it was helpful, thanks for watching!

[@michaelkemp9358]

I got a question and need help bad even my mechanic shop cant figure it out.. i have po 171 code on my 2001 toyota celica gt .. they change the maf sensor and the intake manifold,pcv valve oil change and filter and still the light came on. I dont want to keep spending money on something i dont need. What else can be left they said the hoses are good so the last two things is the o2 sensor and fuel injectors. What do you think it might be

[@8020Media]

M - It could be either of those that you mentioned at the end. Unfortunately, it's a little difficult to pinpoint what it is without any symptoms listed.

[@deajahbell5505]

Hey mine is paired with P2070 (intake manifold tuning valve stuck open bank 1). Are they the same thing and what is the best way to fix both of these if they are two individual problems?

[@8020Media]

D - They aren't the same thing, but the P0171 is likely being caused by the P2070. If you fix P2070, it is likely that the P0171 will go away. Not sure what vehicle you have, but this may be helpful: kzbin.info/www/bejne/pIG0gXmwgZhqnKM

[@Flamunio]

I have this code and it says missfire on bank 1? What is the likely fault? I don’t notice any missfires and a mechanic has seen all number on his computer and says they look okay… also my engine light comes and goes? Also car seems to run fine… mechanic said it could be that the system dirty, or the cat convertor, so try some system cleaning stuff first? Not sure if i had code P0506

[@8020Media]

F - I would listen to your mechanic.

[@p.p2295]

Yes I've been today a few hours ago had my Part fitted. (Purge valve) picked up car after paying £238.00 Me and my partner drove back home which is a few miles away. Car drove like a New one again. Very happy about it. They fixed and reset program. But upto yet. This Purge valve replacement has done the trick upto yet. The mechanic gave me a copy of what he did. Plus they mentioned that driving about before I had it fix may have caused problems to over parts in my engine ? But I hope not. P.

[@8020Media]

P - Thanks for coming back and sharing your experience! We're glad they could fix it up for you.

[@p.p2295]

Yeah Thanks. But it was strange how the Car were running good and no signs really. But the two codes were saying different. But the astra GTG. Is running even better than it was doing. P.

[@8020Media]

P - Nice! Happy it's back to normal.

[@AKidOnARoof314]

I drive a 2018 supercharged BRZ. This code ended up pointing to my supercharger bypass valve failing (the valve is stuck open).

[@specialkfouryou]

I have the p0171 code on my 2009 wrx along with a number of dash lights including the check engine. A symptom that goes along with this (not sure if its the cause or seperate) is, when I get gas the car stalls out and wants to keep stalling for the first couple half mile or so after. I have read there is a vent valve that can cause this but again not sure. I also read something about fuel pump filter. I have started to notice the car making a whining noise as well. Any help would be greatly appreciated!

[@8020Media]

K - We think this video may be helpful for your research: kzbin.info/www/bejne/bZPUcnyYjreXpMU

[@specialkfouryou]

Thank you! @@8020Media

[@stewartbender98]

So I’m getting bank one too lean. No other codes. If it was mad air flow wouldn’t I get both? Should I replace O2 sensor on that side?

[@8020Media]

S - Mad air flow? This mean a lot of air flow?

[@user5511_]

I have both codes, can it be the MAF sensor? Is it a waste of money if i change it or should i give it a try?

[@8020Media]

U - What other code? 0172?

[@user5511_]

@@8020Media No just p0171 & p0174

[@p.p2295]

Been to technician with Po171 code on vauxhall astra gtc. He said it's the purge valve that stuck open ? He said it's a main dealer part. He's ordered it. It will cost £231.00. For part & Labour. Is this about right. PO171 code. Problem. P. P.

[@8020Media]

P - Could certainly be the cause and it isn't wildly expensive, so keep us updated.

[@p.p2295]

Repairing tomorrow so hopefully it will fix this engine light & po171 code & po458 code that the rac man came up with on his machine (scanner) ​@@8020Media

[@p.p2295]

Yeah will keep you informed as the Purge valve is going on at garage tomorrow. He did say that its this part I need after the disnostic report from him. My car is showing no signs of faults. Only engine light on. Plus 2 code po171 & po458. ? See what happens after repairs done. P. ​@@8020Media

[@jaylinjackson9072]

Wha if u replace all o2 sensors,filter and a tune up

[@8020Media]

J - This could solve it, but not a certain.

[@EmWarEl]

Check your air filter cover and connections. The code came up for me simply because one of my air filter cover latches wasn't fastened. $0 fix.

[@8020Media]

E - Great shout! Thanks for sharing this feedback.

[@Faisal.MatarX]

I saw the same with mine

[@Ezecuh]

Mine has this code ( and it causes a misfire, it has rough idle, misfire in cylinder 5 and cylinder 2. Someone please help I changed the ignition coils and I don’t think that was it someone please help.

[@8020Media]

E - Did you change the spark plugs?

[@Ezecuh]

It also has system too lean on bank 1

[@8020Media]

E - Did you go through the steps in the video?

[@Ezecuh]

@@8020MediaIt all leads to sparkplugs, however system too lean came on after I changed the ignition coils and I only have 6 aftermarket’s(edelbrocks) on and 2 Oem ones on

[@danharris5873]

Put BG 44k cleaner❤ in my fuel tank and not too many miles later I'm showing the 0171 2002 Toyota Camry 110,000 MI 2.4 L engine code? Is this just a coincidence

[@8020Media]

D - Give it a 50-100 miles and see if it's still there.

[@Imjustme611]

I replaced fuel pump both 02 sensor MAF spark plugs injectors and still getting code. Car runs better no issues I’m tired of buying parts what’s next??????

[@8020Media]

I - Have you reset the code? How long have you driven after replacing all those parts?

[@Imjustme611]

@@8020Media maybe 200 miles

[@Imjustme611]

Yes reset code but it’s a permanent code?

[@8020Media]

I - Thanks for sharing your experience. Give it some more miles and keep us updated. So long as you aren't experiencing any symptoms, it should be okay. Or can take it to a mechanic.

[@kabbak]

If you have an obdii reader paired with an app(program) on your phone, see if it made a difference with the long term fuel trim. Might need to find the acceptable range for your vehicle

[@michaelkemp9358]

Only thing is im losing gas and little rough idle that about it everything else is running good

[@8020Media]

M - Thanks for sharing your experience!

[@john-lukefenn4909]

I have this on my mrs and the engine light only comes in at 100kmph it's weird

[@8020Media]

John - Do you have any other engine codes?

[@JamesAutoDude]

Could be a vacuum leak or some kinda sensor