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Error code p0171

33K views 17 replies 5 participants last post by  nlester 
#1 ·
Hello I just started getting the error p0171 lean on bank 1 I took it to the stealer and they told me that I needed a new maf and they wanted $400 to fix it, since this is an easy fix I bought the sensor for $70 and did it myself. I cleared the code and it has come back again, I do not have any rough idle or stalling or issues starting like I have read in other post with this issue. My mileage per gallon does not seem to be bad either I had to order an upstream 02 sensor since no one but the dealer carried them but they want $95 for it. I am only getting that one code if anyone can help I would really appreciate it.
 
#4 ·
No I should get it on tuesday but its driving me nuts that I cant get that error cleared. From what I have been reading it could have been the maf which I replaced the map sensor, or the o2 sensor. Since we only have 2 o2 sensors will it only thow out bank 1 codes ir does it still throw bank 2 codes.
 
#5 ·
I would have gone w/ the 02 sensor first.. but thats just past experience..

and I also have seen the trouble code say one bank, when it meant the opposite bank.. dunno why... just that these trouble codes are not always that accurate...

if the 02 sensors were not expensive, I'd just do them both... but it if doesn't clear the code.. then consider the 2nd one ..

post if it fixes it...
 
#9 ·
p0171

I have been dealing with a p0171 for weeks now. I have replaced the MAF sensor, Upstream 02, and the air filter to remove the black ring filter they say can set the code. I have checked for vacuum leaks and there are none. I have performed an AFITS test and the injectors and fuel pressure are good. Also have cleaned the injectors just to be sure. No driveability with the vehicle at all, runs great. The long term fuel trim is up to about 17% sitting at idle. Which from what I understand will set the code if above 10%. Now it seems the only time it sets is if I let it run to warm it up for approx 10 min since it's 10 degrees outside and sets everytime. Thinking maybe a crack in the plastic air intake that only shows itself when its cold. Any thoughts?
 
#14 ·
P0171

Is the only code P0171? As far as where the loose bolts were: The bolts retaining the plastic intake manifold Drivers side of the engine. You should be able to reach most of them especially at cyl 5,6 since they are the closest to the firewall. Move the ECM and bracket to gain access to the rest. The only one not reachable is the front one since the alternator is blocking it. We found most of the bolts about hand tight which would also explain why it has only showed itself when it's cold outside since the intake is plastic and contracted when cold. As far as watching the fuel trims you need a Tech 2. Understandably not something everyone has access to. Let me know what you find!
 
#15 ·
Loose bolts

So right when I read your post about the bolts I went out and checked mine and sure enough the ones that I could get to were loose. The one right before the firewall was so loose I could wiggle it around. I tightend the ones I could reach and this weekend I am going to go through and check them all. I dont understand how they just came loose I wonder how many more envoys have this issue? As far as the error codes yes the only one that is on is p0171 I had it scanned at autozone, advanced auto parts and through onstar. If the loose bolts were the issue should the cel go off on its own or should I disconnect the negitave battery terminal?
 
#17 ·
P0171 fixed

Thanks so much for posting that info after tightening the manifold bolts the error has cleared. If i would have taken it to the dealer they would have told me that I needed a new gasket or something that would have costed me a boat load of money. I almost want to call the dealer that I took it to the first time and let them know that they were way off with their diognastics they told me it was a bad MAF sensor. Thanks again !!
 
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