P0171 code without rough idle

7682 Views 4 Replies 3 Participants Last post by krush, Nov 23, 2015

krush

Discussion Starter · Nov 17, 2015

Hello all,

I recently purchased a 2012 Cruze LS with a 6M and have had a nuisance P0171 code pop up occasionally but doesn't stay on after cleared. It seems to show up when performing a cold start (sitting more than 3 hours) but doesn't seem to affect performance while driving or when idling while warm as I've read in other posts.

Everything I've read about the lean code is that it is an air intake post-MAF leak. I've looked but it does not appear to be a leaking connection.

One thing that was mentioned that my car does is that the RPMs do not immediately drop to idle after letting off the accelerator to shift or stop. It drops quickly to about 1500 RPM but slowly drifts down to ~900 RPM over the course of a few seconds. The gas mileage isn't what I'd expect after having seen the trip from the previous owner's MPG which leads me to think there was a developing problem before it was traded in.

Thank you in advance for any help!

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Robby

· #2 · Nov 17, 2015

With the 1.4t engine, the code ends up being the result of a failed pcv diaphram and sometimes a failed check valve in the intake manifold in conjunction.

Your 1.8 is not known for setting this code.......it is a lean code but there has been no pattern of failure to guide you.
Most likely though, once determined what the actual failure is, it'll likely be a 5/100 powertrain type repair.

Let us know what resolves it for the knowledge base.

Rob

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krush

Discussion Starter · #3 · Nov 18, 2015

Thank you for the reply.

I'm curious if there might be a plugged injector or air in the fuel line that i would get a short injection on one cylinder occasionally near startup. My previous car did not have a fuel pump in the fuel tank and would suck air occasionally at the connections to the fuel filter but never exhibited any symptoms, such as this car.

The snapshot of the code said it occurred at 735 RPM, if that is any help.

A mechanic friend mentioned that the 1.8L on the cobalt has throttle body issues and a thorough cleaning might solve the problem. What are your thoughts on this?

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Vetterin

· #4 · Nov 18, 2015

Have you tried cleaning the sensor?

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krush

Discussion Starter · #5 · Nov 23, 2015

Vetterin said:
Have you tried cleaning the sensor?

Yes, the code cleared. It's been a week since the code flagged a second time. I'm trying to find a longer term solution than cleaning a sensor every month or solve the problem if there really is one.

My '00 jetta didn't need that kind of attention until I got rid of it for the same reason, repeat CELs at 270k mi.

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