I cannot get this code to go away. It keeps coming back. I've swapped out the MAF sensor with another one, cleaned it with MAF cleaner, K&N OEM replacement air filter, what else can be causing this code? 
P0171 Code Cleared!! Problem Solved!!!
Check really carefully for bad vacuum hoses. For me, it came down to a crack on the bottom of the PCV hose. I'd done maf, O2, etc. but it came down to that hose. You could have a leak at either end. If you havent changed your pcv valve, it could be that or a bad grommet. Get a spray bottle with soapy water, spray the hose connections, watch the bubbles and listen. I fought it for months and the pros never found the leak.
Driver
Joined: Jun 2004
Posts: 142
Likes: 3
From: Texas
My wife found a receipt from Autozone.. the one they print out that shows the code and what might be causing it. Its P0171, and its dated December of 2008. Apparently I was battling the P0171 for longer than I realized.
Instructor
Joined: Feb 2002
Posts: 956
Likes: 3
From: New Jersey
Driver
Joined: Jun 2004
Posts: 142
Likes: 3
From: Texas
P0171 on a gs4 is coming from the driver side cylinder bank. Thats where the PCV valve is. It was a split in the PCV hose that caused mine. Since thats the side farthest away from the air intake, it could be related to the air intake. There are three small hoses that come off the air filter/resonator. You might want to check those too. One in particular, coming off the back of the resonator is notorious for breaking off. Could also be the fore O2 sensor on that side too.
I'll be interested to hear if its the PCV hose.
I'll be interested to hear if its the PCV hose.
Driver
Joined: Feb 2003
Posts: 51
Likes: 0
From: Arizona
Thanks Fasted!
I'll check that out after work today. I cleared the code and so far it hasn't popped back on. I did notice the K&N intake has an AEM dry filter on it and someone oiled it!! Maybe I'll clean the filter and the MAF too just in case?
I'll check that out after work today. I cleared the code and so far it hasn't popped back on. I did notice the K&N intake has an AEM dry filter on it and someone oiled it!! Maybe I'll clean the filter and the MAF too just in case?
I had this code come up right after refueling. I noticed a huge release of pressure when removing the fuel cap (car was still running). The light was on when I got in the car. After about 50 miles, the light is now off.
I've refueled with the car running before and it hasn't done this, maybe it's just due to the extremely high temperatures recently?
I've refueled with the car running before and it hasn't done this, maybe it's just due to the extremely high temperatures recently?
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Driver School Candidate
Joined: Aug 2010
Posts: 2
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From: illinois
I checked all things and rechecked, then i used a smoke machine and i found that the leak was from intake manifold by #7 cylinder. Removed and cleaned top and bottom intake manifold. Make sure You change all intake gaskets including secondary air pump which is located in the back of the top portion of the intake manifold. Problem solved. I was fighting this problem for couple months. Even the dealer could not tell me why i'm gettin P0171 code.
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