Code P0171

SBMISRY

MEMBER
2003 PONTIAC GRAND AM
3.4L
V6
2WD
AUTOMATIC
186,509 MILES

Replaced: vacuum hoses, intake manifold gasket, new spark plug wires, new spark plugs, fixed exhaust leak, new PCV valve, new MAP sensor. I am still firing a p0171 code. It was happening frequently but since the MAP sensor replacement it's only happening at very low speed. I will list the freeze frame details: fuel system- CL, calc load- 3.1, ect- 122, stft- 0, ltft- 21.8, map- 9.7, eng rpm- 850, veh speed- 0, maf-.68, tps- 0. I'm monitor status is showing 2 red icons.C and ev. Any ideas what to change next?

5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

Can you give me the long-term trim for the O2 sensor, bank 1?

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

I would also check the fuel pressure. Low pressure is a very common reason for the lean codes.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Roy

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Friday, February 26th, 2021 AT 8:13 AM

SBMISRY

MEMBER
60 POSTS

I don't think believe the reader I have does that.

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Friday, February 26th, 2021 AT 9:59 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

It is in the first picture. It is 21%.

Make sure you check the fuel pressure.

Roy

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Friday, February 26th, 2021 AT 11:11 AM

SBMISRY

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60 POSTS

What should it be at?

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Friday, February 26th, 2021 AT 12:12 PM

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

Here is a tutorial showing how to test fuel pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you don't have access to a fuel pressure tester most auto parts stores have tool loaner program and can rent you one. The fuel pressure specification for your car is 52-59 PSI. After performing this test get back to us with the results and we'll go from there. Hope this helps and thanks again for using 2CarPros.