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Code P0171 lean code at idle?

Tiny
JACK1999
  • MEMBER
  • 2016 SUBARU FORESTER
  • 2.5L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 95,000 MILES
I have attached some live data and a freeze frame when the lean code was set. Although the DTC is a lean code the a/f precat sensor and postcat o2 sensor seem to show a rich situation. I may be misinterpreting the data. Hope you can help. I have attached the data.
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Sunday, April 2nd, 2023 AT 10:32 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,959 POSTS
I don't see the data images uploads can take a few seconds so be patient. Can I ask how the engine is running? A misfire might cause this problem. Also, I would check for vacuum leaks.

Here is a guide to help but only use it with the engine cold:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, this guide can help as well:

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

Please go over these guides and report back.
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Monday, April 3rd, 2023 AT 11:45 AM

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