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2005 PRIUS P0300, P0301, P0302

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by FM1775, Jan 1, 2023.

  1. FM1775

    FM1775 Junior Member

    Joined:
    Jan 24, 2015
    8
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    Location:
    South CA
    Vehicle:
    2005 Prius
    Model:
    II
    250K miles, original gas motor. Codes P0300, P0301, P0302.

    If anybody has some suggestions for the cause of the trouble, please write.

    Things tried:
    -Replace spark plugs.
    Observation- spark plug wells clean and dry. Plug 1 had way more gap due to erosion than 2, 3, 4.
    -Replace coil packs.
    -Replace PCV valve
    Observation- old valve still worked fine
    -Remove intake manifold assembly; clean and reinstall.
    Observation- manifold interior dirty with carbon; this was easily cleaned out. Air flow valve unit had some grime, easily cleaned out. Valve turns easily, spring easily returns valve to home position.
    -Unplug coil pack electrical connectors, clean contacts
    -Unplug fuel injector connectors, clean contacts.

    After doing all the things listed above, here is some info from the code reader.
    Freeze Frame Data:
    P0301
    FUEL SYS 1...CL
    FUEL SYS2...NA
    CALC LOAD (%) 16.9
    ECT(DEG F) ...136.4
    STFT B1(%)...5.5
    LTFT B1(%)...0.0
    ENG RPM...1698
    VEH SPEED (MPH)...2
    SPARK ADV(DEG)...14.5
    IAT(DEG F)...78.8
    MAF(LB/MIN)...0.6
    TPS(%)...15.7
    O2S B1 S2 (V)...0.640
    STFT B1 S2(%)...99.2
    RUN TIME (SEC) 43
    LAMBDA B1 S1...1.023
    O2S B1 S1(V)...3.425
    COMMAND EVAP...0.0
    WARM-UP DTC CLR...0
    CLR DIST (MILES) 1
    EVAP_VP(INH20)...0.272
    BARO(INHG)...29.8
    CAT TE 11(DEG F) ...534.0
    CAT TE 12(DEG F)...228.4
    ECU VOLTS (V)...14.003
    LOAD VALUE (%)...16.5
    EQ RATIO...1.004
    REL TPS(%)...0.0
    AMBIENT(DEG F)...60.8
    TPS B(%)...51.0
    COMMAND TAC (%)...15.7
    CLR TIME...0H11M

    Thanks anybody who may have suggestions. I have basic car repair tools, code reader, multimeter, Haynes book.

    -FM
     
    #1 FM1775, Jan 1, 2023
  2. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,645
    3,858
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    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    Did you clean the airflow sensor as well as the temperature sensor in the MAFS? The temperature sensor is easily seen externally down the side of the probe. The airflow sensor is internal and hidden a little. This post by Mr_Guy_Mann has a good picture showing the airflow sensor pickups.

    Generally speaking miss-fire codes (P03xx) are due to bad plugs, bad coils, or bad injectors. You replaced the plugs and coils. Did you use good quality (NGK or Denso Iridium plugs) and Denso coils? Good quality means not from Amazon or eBay, which if cheap are likely to be counterfeit parts.

    My only other (clutching at straws) thought is a leak in the plumbing after the MAFS that is letting in unmetered air.
     
    #2 dolj, Jan 1, 2023
    SFO likes this.
  3. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
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    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    I would drive the car while monitoring fuel trim numbers. Short term and long term fuel trim should stay close to 0% under most conditions. Does it ever go above +10% or below -10%, if so then when?

    MAF sensor problems, vacuum / induction leaks, or injector problems should all cause abnormal fuel trim numbers.

    Do you feel jerking sensations (stuttering, hesitation) from the powertrain when driving? Does the MIL (check engine light) flash?

    You need to be certain that your ignition system is up to snuff. IF that's provably ok, and fuel trim is reasonable, then you have to look at other possibilities, like head gasket issues, valve clearance out of spec (extremely rare on Toyotas), or a compression problem.

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Jan 1, 2023
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