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P0171

Discussion in 'Generation 1 Prius Discussion' started by EddieAtl, Apr 26, 2015.

  1. EddieAtl

    EddieAtl HYBRIDATL

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    Hi guys!
    I'm having a problem with this code, i've replaced the mass flow sensor but after resetting it, code still coming back. :( Do any of you have had issues with this? Appreciate any assistance! Thank you
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC P0171 means that the air/fuel ratio is too lean. Any misfire codes in the P030x family?

    I would start by looking for an air leak allowing unmetered air to enter the engine, below the throttle body. For example, a loose PCV hose, a missing O-ring seal on the engine oil dipstick or the engine oil cap. Or maybe a bad throttle body gasket where the throttle body bolts to the intake manifold.

    If nothing is found, check the fuel line pressure, which should be at least 43 psi when the engine is at idle speed. If this is good, maybe a fuel injector is partially plugged.
     
  3. EddieAtl

    EddieAtl HYBRIDATL

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    Thank you Patrick! i will check into it.
     
  4. LCH

    LCH New Member

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    May i know your vehicle mileage and fuel learn correction %?
     
  5. DRACO

    DRACO Member

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    +1, check all connections, you may have dislodged a vacuum hose or cracked a brittle one, BTW, what and how did you clean the MAF?
     
  6. DRACO

    DRACO Member

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    Not sure what these means. Can you be more specific as to what you are asking the OP?