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vwtech0405, VW Technician
Category: VW
Satisfied Customers: 10670
Experience:  VW Master Technician VW Certified
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I have a 2004 vw jetta and I keep getting the code P0171. I

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I have a 2004 vw jetta and I keep getting the code P0171. I have changed the maf, 02 sensors, and fuel filter. I have noticed that when it is started it idles like it wants to die out. When you drive and stop the idle drops low and sometimes dies out. I did notice that the crankcase ventilation house from the valve cover is suctioned flat. If there was a leak in the the crankcase ventilation hose would it cause this code? Is is part of the vacuum system that would make the car to run lean? If it wouldn't do you have any other suggestions to fix the problem?
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What engine do you have?
Customer: replied 7 years ago.



Ok first i would replace the crankcase breather hose it has collasped if you look underneath the intake there is a several breather hoses under there that tend to break with time make sure you check that those are not torn . There is also a small vaccum hose that goes to a small port fitting under the intake make sure the hose is not broken. By the way you are describing the vehicle almost dying out it sounds like you have a vaccum leak. If you dont find any broken hoses then what you can do is smoke test the intake to help you out to locate a leak I hope this helps
Customer: replied 7 years ago.

can you please tell me what a smoke test is and how to preform it? I also just took a close look and I see that there is a hole in the crankcase ventilation hose at the "y" for the hose that goes under the intake manifold. Can you tell me if it is possible if a hole in the crankcase breather hose could cause the code?

What i mean by smoke testing the engine is there is a smoke machine that here at the shop we install in any vacuum port into the intake and it puts smoke into the intake and the breather hoses that way its easier to find a leak you probably dont have access to a machine like this.Mke sure you follow and look carefully at all the breather hoses and vacumm hoses under the intake if broken they will give you that code!
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