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Check Engine -- Codes P0300 and P0301; P0304; P0456

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by cyberpriusII, Feb 20, 2017.

  1. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Saturday morning (today is Monday), Prius made a crash boom bang when I started up -- was not sure what it was, but finally, after advice on PriusChat, thought it might have to do with Cold Soak Detonation.

    After the first second or three, the noise disappeared. All seemed well and I drove it some 50 miles on various trips on Saturday and Sunday. No issues, whatsoever.

    This morning (Monday), start it up at home first thing in the morning and all seems fine. Then about 500 yards along, the check engine light came on.

    As noted in the title:
    Codes P0300 and P0301; P0302 P0304; P0456
    <missed one code in my title>

    The P03XX I know refer to cylinder misfiring, which I guess relates back to Saturday morning -- which was cold start from home.

    P0456 apparently says small EVAP system leak. I re-tightened the gas cap.

    Can't seem to paste a screen shot to post...but I finally got an attachment to work, see below.

    Question -- Should I disconnect the negative cable to clear the codes and just see what happens?
    kris
     

    Attached Files:

    #1 cyberpriusII, Feb 20, 2017
    Last edited: Feb 20, 2017
  2. Jmack111

    Jmack111 Member

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    #2 Jmack111, Feb 20, 2017
  3. Stevewoods

    Stevewoods Senior Member

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    Depending on your tolerance for check engine lights, you could just wait three days without pulling any cables -- I think that is the average time it takes the check engine light to go out if it is just a one-time malfunction. Of course, something else may go wrong in the meantime and you would never know. LOL!
     
    #3 Stevewoods, Feb 20, 2017
  4. RRxing

    RRxing Senior Member

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    I see you've been to Florence...
     
    #4 RRxing, Feb 20, 2017
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  5. edthefox5

    edthefox5 Senior Member

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    Yes clear the codes and see if the random misfire comes back. Has the proper oil level been maintained.....what was the oil level when it first made the boom bang. Hope that detonation didn't bust up the bottom end of the motor. Sounded bad. Do you feel any engine vibration when you were driving before it threw the codes?
    The po546 is interesting it's the exhaust gas temp sensor circuit. Wonder what the hell happened there Kris.
     
    #5 edthefox5, Feb 20, 2017
  6. cyberpriusII

    cyberpriusII Prodigyplace says I'm Super Kris

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    Oil level is about 3/4 full, which is where I keep it. It has never used any oil, nor has it ever been low or overfilled. I have done all oil changes myself. Never uses oil.

    There was absolutely no indication that anything was wrong, except for the "bing, bang, boom" of a few seconds on Saturday morning. Followed by two days and about 50 miles of no problems at all. Until this morning and still no problems, except the light came on.

    I did drive about four miles a little bit ago to see if I could detect any issues. No problems, except the check engine light is still on.
     
    #6 cyberpriusII, Feb 20, 2017
    Last edited: Feb 20, 2017
  7. bisco

    bisco cookie crumbler

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    sorry chris, you're out of my league now.:unsure:
     
    #7 bisco, Feb 20, 2017
  8. edthefox5

    edthefox5 Senior Member

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    That's good news lots of times random misfire is due to lower end damage causing vibration and misread and miscalculation of crank and cam sensors pg. Annticipated revolutions don't add up and ecu sees that as dead cylinder and throws misfire nag.

    Keep oil at the full line.

    Put the car in Inspection mode and let the engine run. Let it run to op temp. Take a good listen to it. Listen to it under the front of car paying attention to bad sounds in the basement.
    Listen for subtle misfiring.
     
    #8 edthefox5, Feb 20, 2017
    Tbkilb01 likes this.
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