Code P0171 lean code at idle?

2016 SUBARU FORESTER
95,000 MILES • 2.5L • 4 CYL • 4WD • AUTOMATIC
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JACK1999
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  • 1 POST
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.
Apr 2, 2023 at 10:32 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
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.
Apr 3, 2023 at 11:45 AM
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