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Greg, Technician
Category: Lexus
Satisfied Customers: 8146
Experience:  Import tech
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What does it mean when the diagnosis says " P0171 system too

Customer Question

What does it mean when the diagnosis says " P0171 system too lean (bank 1 )
Submitted: 4 years ago.
Category: Lexus
Expert:  Shantal-Mod replied 4 years ago.
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Expert:  Greg replied 4 years ago.
Name is***** goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back,

Hi P0171 could be quite a few things that would trip this code.

The engine air/fuel mixture is too lean,

There is too much air or too little fuel.

Common causes:

  1. Intake or vacuum leaks
  2. Clogged or faulty Mass Air Flow sensor (MAF)
  3. Faulty PCV valve
  4. Stuck open purge valve/solenoid
  5. Failed or faulty oxygen sensor (bank 1, sensor 1)
  6. Improperly installed aftermarket cold intake
  7. Low fuel pressure
  8. Clogged catalytic converter
Sometimes this code can be caused by a bad MAF sensor ,might be a good idea to check this and clean it with MAF spray cleaner .

Then clear codes and test drive if the check engine light stays off then all is good if it comes back on check for codes ,still a P0171 then check the other possible causes .

Please get back to me with the reply button, and not the poor or bad service, this way i can get back to you or suggest another expert if needed.

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Not rating or a bad rating does not constitute a refund, if you are not happy or you have sorted out your problem before the answer then please let me know.

Kind regards Greg.