07’ Vibe with infamous P0171

[BethanyWashingtonCo]

My girlfriend’s vibe has thrown out codes on an off for about two years.

Before I started helping her she had a gas cap replaced, then the MAF, O2 sensor replaced.

Now we have to get an emissions test done, and I’ve been trying to pin point the cause.

At first we did the intake manifold and valve cover gasket, then we did the pcv valve, and at this point the light has gone away.

So, I wanted to confirm the fix and I used a scanner- long term fuel trim is down from 30% to 15%and short term is between 1-5% down from 20%.

So things look good, but the trim is still high, and the MAF is reporting 1.65 g/s of air.

The g/s goes up at 2500rpm and the fuel trip goes down to about 9% long term.

It seems like I might still be dealing with pirate air, or maybe I should try another new MAF. Our next project is the fuel pump assembly and put some fuel injector cleaner in the tank. But, given my understanding of fuel trim levels I don’t think we have a fuel delivery issue.

Any suggestions are appreciated.

[CRzepecki84]

I have been fighting this very issue on my 06 Vibe Base. It seems I have to keep replacing the MAF Sensor every 6-8 Months. (Thankfully a lifetime warranty) It's good for half a year, then right back to the same P0171. I chased the problem for months back in 2024. Replaced the Fuel Pump Assembly, new injectors, Intake Manifold Gasket, V/C Gasket, O2 Sensors, basically everything associated with that code. Mind you I had just changed the MAF about 5 months prior, so I didn't suspect that. But after still having the code and rough idle, I cleaned the MAF and it was better. So I warrantied out that one. All was good until about 2 weeks ago. Same issue. It really seems to throw the Check Engine light when idling for longer than 10 - 15 Minutes. Roughish idle between 700RPM and 1300RPM. It'll go up and down at random.

I wanna say I read something a while back that GM/Pontiac had a TSB/Recall for this issue with the P0171 and rough idle. I think they were reflashing the PCM with an update and that resolved the issue. Not sure if that's completely true, but I am tempted to go to my local GM Dealer and ask about it.

I'll update if I find out anymore info.