# CEL P0171, P0174



## ARS267 (May 28, 2007)

the codes are System to Lean Banks 1 & 2. What would cause the engine to run lean? Everything is stock on my '01 4.2


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## Massboykie (Aug 15, 2006)

*Re: CEL P0171, P0174 (ARS267)*

Hey AR
Perhaps some other 4.2 guys knows what usually causes these, butdid you use a VAG-COM or generic reader? If you used VAG-COM, I would do an autoscan see if anything else is throwing errors, or check what your readiness looks like.
Cheers
Massboykie


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## GLS-S4 (Jun 6, 2005)

*Re: CEL P0171, P0174 (ARS267)*

If your unsure when they were last changed, you may want to try a few *simple* things like replace the air filter and fuel filter.
Failing that, I'd try a Fuel Pressure test to verify fuel pump, inspect for pinched fuel lines, etc
I'd be curious to do a running log with VAG and see when engine goes lean, as in during higher RPM WOT only, all the time, weather related, etc.
Don't leave it too long, engines running lean for a long time have high repair bills!



_Modified by GLS-S4 at 12:41 PM 3/5/2008_


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## ARS267 (May 28, 2007)

*Re: CEL P0171, P0174 (GLS-S4)*

i've posted on audizine and they ssaid to try cleaning the MAF. They also said it may be o2 sensors. Ill have to get one of my friends help me log it since i don't have vag-com.


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## ARS267 (May 28, 2007)

*Re: CEL P0171, P0174 (ARS267)*

I was taking my maf out to day to clean it and i noticed this diaphram with a rod connecting it to an actuator had a broken rod...
















and to show where it is....


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## thetwodubheads (Dec 6, 2004)

*Re: CEL P0171, P0174 (ARS267)*

I know as far as BMWs go, that code pops up all the time on the V8s with o2 sensor issues. They may not be gone enough to throw a code, but off enough to be running the car funny.


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## ARS267 (May 28, 2007)

*Re: CEL P0171, P0174 (thetwodubheads)*

thats what i've heard, but im holding out on it being a MAF issue. When i turned the CEL off the first time it came back after 20 miles, but after i cleaned the MAF it took about 60 miles for it to come back. Mabey a jsut a considence. Thanks, for the help.


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