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pls help Intermittent P0300, p0301, and p0302

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by shtbox, Jun 6, 2023.

  1. shtbox

    shtbox New Member

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    Hi friends,

    I got a 07 prius at 158,000ish miles and its been having the cylinders 1 and 2 misfire for a few days, then the CEL will go away for a bit. Ive replaced the spark plugs and ignition coils, and I ran a compression test on it (all the cylinders were at like 145ish psi). In the beginning, some friends recommended switching coils 1 and 2 with 3 and 4, which seemed to fix it for a few weeks, but the problem is back. I feel like its not the fuel injectors because the mpg has never dropped, but idk for sure. I just need to get it smogged, and if the problems not serious ill keep driving on it. If possible, I'd prefer to do the work myself to save $$. What are your thoughts?
     
    #1 shtbox, Jun 6, 2023
  2. PriusCamper

    PriusCamper Senior Member

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    Have you ever had problems with low oil?

    Like 2 quarts low on oil? Crankshaft bearing vibrations will trigger misfire error codes if they're lacking oil...

    Also switching the coils around wasn't recommended to eliminate the misfire, but to determine which coil was bad. So if the problem came back you should have enough information to determine which coil is bad/if coil test is inconclusive.
     
    #2 PriusCamper, Jun 7, 2023
  3. shtbox

    shtbox New Member

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    It eats oil like any other old toyota but I fill/change it before it gets too low or dirty. And yea I switched it to see if anything changes, which it seemed like it did for a while but since its the same cylinders misfiring after switching I'd say inconclusive
     
    #3 shtbox, Jun 7, 2023
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    That points to head gasket failure. Are you sure this isn’t a gen 3 lol, head gasket letting go on cylinders one/two is their MO.
     
    #4 Mendel Leisk, Jun 7, 2023
  5. PriusCamper

    PriusCamper Senior Member

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    Try switching coils around one more time just to be certain... Probably next step after that's confirmed is doing compression test / leak down test.

    Also how did the previous spark plug look on the cylinder that's misfiring despite it having a different ignition coil?
     
    #5 PriusCamper, Jun 7, 2023
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