P0171 error code

Tiny
KEN JAMES
  • MEMBER
  • 2005 NISSAN SENTRA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 273,000 MILES
About a month ago the “check engine soon” light came on. I pulled the code and it comes up with a P0171. I read just about everything there is to read on the internet about the P0171 code and I am so confused now. So far I have changed the air filter, cleaned the MAF sensor, replaced the PCV valve, it was kind of gummed up, put a can of Sea Foam in the gas tank and checked all the connections and hoses. I can clear the error code drive the car all over town for days and the check engine soon light will not come on, when I get on the freeway it will come after about two or three miles of driving on the freeway. The car runs prefect and is in excellent condition. I am at a loss, I do not know what to do or direction to go in now, I am an old Vietnam veteran on a very fixed income.

Thanks for any help or direction you can give.

Randy
Tacoma, WA
Friday, December 8th, 2017 AT 2:35 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,663 POSTS
Three things are the main cause of the lean condition. First is an engine misfire I know you said it is running good put if you have not installed a new set of plugs in a while this is where I would start. Next I know you said you cleaned the MAF but most of the time they are too far gone to be cleaned and need to be replaced. Third is low fuel pressure from the fuel pump.

Here are a few guides to help us get started fixing the problem:

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

and

https://www.2carpros.com/articles/how-to-change-spark-plugs

and

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Please run some tests and get back to us.

Cheers, Ken

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Sunday, December 10th, 2017 AT 11:08 AM

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