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P0401 - insufficient egr flow - what to tell mechanic?

Discussion in 'Gen 3 Prius Main Forum' started by Steelerfan2018, Apr 2, 2022.

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  1. Steelerfan2018

    Steelerfan2018 Member

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    Hi all,
    I just got the p0401 check engine light - insufficient EGR flow. I need to get the car inspected, so will be taking into the shop. Some Qs.

    2011 with 145k miles.

    - am I safe to keep driving it? Or should I park it until I put it in the shop? Is there anything I can do in the short-term to help? Like a fuel additive? It is probably going to take a few days before my mechanic can see the car.
    - What should I tell my mechanic to check? I assume the EGR - but anything else?
    - Will a catch can help? Should I get my mechanic to install one? If so, does anyone have a recommendation?

    Ironically the car is running great - getting about 42mpg but it is using oil (which seems to be par for the course with gen 3 priuses).

    Thanks,
    Rob
     
    #1 Steelerfan2018, Apr 2, 2022
  2. bisco

    bisco cookie crumbler

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    you need to clean the entire egr circuit. it could blow a head gasket, idk if you should drive it or not.

    catch can will help too.

    see @NutzAboutBolts youtube video
     
    #2 bisco, Apr 2, 2022
    Last edited: Apr 2, 2022
  3. ChapmanF

    ChapmanF Senior Member

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    Don't clear the code. Now that the engine control module knows there is an EGR flow issue, it will control the engine more gently to avoid damage.

    Any risk of engine damage (head gasket or other) would have been higher just before this code was posted. ;) And if you clear the code, it will be higher again. So don't do that.

    And yes, the EGR passages (cooler, valve, pipe, manifold) will have to get cleaned out. Don't overlook the ones in the intake manifold itself.

    The cooler is tedious to access; that's a big chunk of the labor in the job.
     
    #3 ChapmanF, Apr 2, 2022
  4. Steelerfan2018

    Steelerfan2018 Member

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    Wow you guys are fast. When you mention EGR passages - is there a specific name for the cooler? Trying to be as specific as possible with my mechanic.

    Also is this what I am looking for?

    for a catch can?

    Bisco - thanks for the warning. Checking the youtube vid now.
     
    #4 Steelerfan2018, Apr 2, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    #5 ChapmanF, Apr 2, 2022
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Check first link in my signature
     
    #6 Mendel Leisk, Apr 2, 2022
  7. Steelerfan2018

    Steelerfan2018 Member

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    Thank You Mendel - great links.
     
    #7 Steelerfan2018, Apr 4, 2022
  8. taxidriver50005

    taxidriver50005 Active Member

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    All good advice, clean entire EGR circuit, oil burning can be sorted by by doing a piston soak with a good cleaner ( I use liquid molly pro engine flush) and doing a engine flush regularly... I have 2 x prius one has 240, 000 miles other will hit 300,000 miles this week and neither burn oil.... One car was a heavy drinker before the piston soak treatment.

    Posted via the PriusChat mobile app.
     
    #8 taxidriver50005, Apr 10, 2022
    Michael Wood likes this.
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