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PO 300, 303, 304

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Sippy Theut, Dec 21, 2017.

  1. Sippy Theut

    Sippy Theut New Member

    Joined:
    Dec 21, 2017
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    Location:
    Virginia
    Vehicle:
    2011 Prius
    Model:
    Two
    I have a 2011 with around 141, 000 miles on it. I drove all day two days ago with no problems. Yesterday, I pulled it out of the driveway and parked it on the street. The temp was in the 30's-40's with overnight in the 20's. My daughter went to drive it last night and we immediately heard a loud knocking and thunking (?).

    Today, my son and I checked the oil. It was low. We put in 3 quarts. After letting it run, the thunking stopped.

    After my husband came home, we went back out to check it and test the codes. I drove it a very short distance (less than a block) and the check engine light came on.

    The codes are PO 300, 303, and 304.

    We reset the code. Thoughts on where I go from here?
     
    #1 Sippy Theut, Dec 21, 2017
  2. tankyuong

    tankyuong Senior Member

    Joined:
    Nov 9, 2012
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    Location:
    Central MO
    Vehicle:
    2012 Prius c
    Model:
    II
    che k your egr system its probably clogged
     
    #2 tankyuong, Dec 21, 2017
  3. bisco

    bisco cookie crumbler

    Joined:
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    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    welcome!
    keep a close eye on the oil level. start with everyday, and slowly back off until you get a comfort level on how fast it is burning.
    now that you let it get so low, a new engine may be in your future, unfortunately.
     
    #3 bisco, Dec 21, 2017
  4. JC91006

    JC91006 Senior Member

    Joined:
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    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    The car only holds 4.5 quarts of oil, if you added 3 quarts, it probably was low enough to cause some permanent damage to the engine
     
    #4 JC91006, Dec 21, 2017
    danlatu likes this.
  5. danlatu

    danlatu Senior Member

    Joined:
    Apr 27, 2017
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    Location:
    maryland
    Vehicle:
    2011 Prius
    Model:
    Two
    Your plugs are fouling from misfire caused by one of two things. Burning oil or coolant. Condensation/oil in intake manifold is sucked into the combustion chamber on start up causing the knocking. Does the car idle smooth after a minute during a cold start? If so, take out and clean the entire intake manifold, egr pipe, egr cooler, pcv hose and install an oil catch can.
    What level is your coolant reservoir at? If it is low, You are most likely burning coolant causing misfire and may have a blown head gasket.
    I am ruling out dirty injectors because it happened when it was cold out and am leaning towards oil in the intake plenum from pcv system.
     
    #5 danlatu, Dec 21, 2017
    RMB and m.wynn like this.
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