# P1101 0171 2635 069e



## Robby (Mar 1, 2013)

Since you indicate the P0171 is the first code, only focus on that one. Following codes, pending or displayed, generally are resultant of the primary problem.

Any vacuum leak will set the P0171 so inspect by looking at all vacuum lines, either a rub through where a line touches something or a crack at one of the attachment nipples......any line originating from the intake side is suspect.
You are going to have to try harder to figure out if the check valve is still in the manifold and based on the model year and mileage and the high failure rate of the earlier design, I would not be shocked if it is the main culprit.
You indicate a cam cover (pcv) replacement has occurred and the newer covers have a more robust diaphragm but it still will fail if under constant vacuum from a failed check valve......just not as catastrophically.......visualize a small tear causing a small vacuum leak as opposed to a full, end to end tear causing a massive vacuum leak.

FWIW, the new manifolds have a metal ring attached internally to keep the check valve in position.......the original design just had the plastic kind of melted around the valve and as it got brittle over time (and heat) the edges created from the melting process broke off, allowing the plastic valve to go.........well, no one knows where it ended up but I believe ingested, burned up, blown out......whatever, it disappeared.

Anyways, diagnosis from afar, if no vacuum lines are damaged, a manifold and cam cover are likely the issue.

Rob


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## unitednations161 (Mar 13, 2011)

Alright thats good tho know, I probably could do an intake at the apartment, but not a fuel pump. I will clean that intake out to check the valve this weekend, probably if I feel better.


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## unitednations161 (Mar 13, 2011)

I cleaned the intake out, the check valve is there.


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## unitednations161 (Mar 13, 2011)

Cleaned everything code came back on on a rough Start, this time the P2635 was the first code.


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## Robby (Mar 1, 2013)

Low fuel pressure code......either the pressure relief has failed, the vacuum line to it is leaking, or the in tank pump is below spec.
This code, and rough (mimics misfire.....) operation result.
You are close to doing 'Shotgun' repairs....ie, shoot parts at it till resolution......might want to consider a dealer trip to prevent needless expense and brain damage.

Rob


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## unitednations161 (Mar 13, 2011)

Robby said:


> Low fuel pressure code......either the pressure relief has failed, the vacuum line to it is leaking, or the in tank pump is below spec.
> This code, and rough (mimics misfire.....) operation result.
> You are close to doing 'Shotgun' repairs....ie, shoot parts at it till resolution......might want to consider a dealer trip to prevent needless expense and brain damage.
> 
> Rob


Yes, fuel pump the worse of anything, but I cant figure out why the first time the MIL was on the code was 1101 and just that, Second time, 0171 with 2635 pending, and this time 2635 with 0171 pending. 


Yes, I think thats whats in order. Although the 100 dollars for a dealer to check it would buy a few "shotgun" parts.
Ill check independent shops around here.


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## jblackburn (Apr 14, 2012)

1101/0171 together are usually a vacuum leak or failed valve cover (PCV)/


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## unitednations161 (Mar 13, 2011)

jblackburn said:


> 1101/0171 together are usually a vacuum leak or failed valve cover (PCV)/


I could see that easier than a fuel pump, The car will start on a cold start, Meaning the temp is below 40, after sitting a while, and High idle wicked rough, the Rpms will keep trying to drop. If i push the accelerator if revs smoothly, if It was lacking fuel wouldn't it stumble more? 

I dont understand the p2635 code, and don't know if I should take it in with that code the main one. I almost want to reset it again and try to get the p0171 code to be the one on the freeze frame.


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## jblackburn (Apr 14, 2012)

The PCV is fortunately an easy test - usually the disc under the spark plug cover will be hissing if that's your issue. The missing check valve in the intake manifold may cause this issue too...a few Q-tips and some solvent could confirm whether or not it's there.

Not really sure about the fuel pressure code; I would try the filter first. I wonder if it could be tripped by an erratic idle...


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## unitednations161 (Mar 13, 2011)

jblackburn said:


> The PCV is fortunately an easy test - usually the disc under the spark plug cover will be hissing if that's your issue. The missing check valve in the intake manifold may cause this issue too...a few Q-tips and some solvent could confirm whether or not it's there.
> 
> Not really sure about the fuel pressure code; I would try the filter first. I wonder if it could be tripped by an erratic idle...


PCV doesn't seem to be hissing. Check valve is there, 

Filter is in the tank though correct?


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## jblackburn (Apr 14, 2012)

unitednations161 said:


> PCV doesn't seem to be hissing. Check valve is there,
> 
> Filter is in the tank though correct?


Crap, you're right. Sorry, thinking of another car. 

I guess next I'd start looking for a vac or air leak of some sort. 

Poking around some GM Bulletins, it appears that the 2635 may more often be just a bad sensor than the pump. 

Sent from my SM-G950U using Tapatalk


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## unitednations161 (Mar 13, 2011)

jblackburn said:


> Crap, you're right. Sorry, thinking of another car.
> 
> I guess next I'd start looking for a vac or air leak of some sort.
> 
> ...


where are these GM bulletins? what sensor?


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## jblackburn (Apr 14, 2012)

unitednations161 said:


> where are these GM bulletins? what sensor?


https://gm.oemdtc.com/3236/dtc-p2635-with-p018b-2014-2015-cadillac-chevrolet-gmc

Here is one. I also saw one for 2013-14 Impala and CTS with the 3.6. I don't know if the sensor is a shared part or not.


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## unitednations161 (Mar 13, 2011)

Interesting.


I just find this strange, I reset the light again, and now that its above 40 it started and idled fine, and no MIL. But a pending p0171 and nothing else.


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## unitednations161 (Mar 13, 2011)

I have read that intake gaskets leaking could be worse the colder it is out.


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