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P0401, can I drive it safely?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Johhhn, Oct 31, 2022.

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  1. Johhhn

    Johhhn Junior Member

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    My 2011 got the EGR code a few days ago. Is it safe to drive like this? I plan on ordering a new EGR valve, cooler, intake manifold, PCV, and spark plugs. Not sure when it'll be in nor when I'll have time to do the job.

    Anyone have links to the updated EGR valve? Thanks!
     
  2. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    What’s the miles on it?

    with the code you might qualify for Toyota’s warranty extension, check with dealership.

    how’s the engine coolant level in reservoir, and any shake on cold start?

    rather than unleashing the parts cannon, everything you mentioned is cleanable. But verify head gasket ok first.
     
    #2 Mendel Leisk, Oct 31, 2022
    Last edited: Oct 31, 2022
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  3. ChapmanF

    ChapmanF Senior Member

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    There's a school of thought that operating without EGR can endanger the head gasket (and a few sub-schools that might differ on exactly how that happens).

    The good news is, once the ECM announces that P0401 code, it knows there's no EGR, and it dials back some operating parameters like spark timing, to keep the engine safer (at a bit of cost of power / MPG). So whatever danger very low EGR flow might present, it was probably higher in the miles just before the P0401 popped up than it is now. You're probably a bit protected as long as that P0401 is showing and you don't clear it.

    Still, I wouldn't dawdle in getting the trouble fixed.
     
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  4. Tombukt2

    Tombukt2 Senior Member

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    So is it more the valve or more the intake probably stopped up along with the cooler and what have you or does that electric valve really go fubar seems to me everything plugs up as in build up.
     
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  5. ChapmanF

    ChapmanF Senior Member

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    The electric valve is very simple, but does have a known way to go fubar that should be checked for. It is easy to check, and if found, the valve should be replaced. (Or you could try to fix it with a bent heated butter knife the way ozmatt did, but that'd count as hardcore DIY.)
     
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  6. Tombukt2

    Tombukt2 Senior Member

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    I guess I would say drop by an LKQ and you'll see these just hanging off the backs of the engines where people have taken the coolers and whatever else a lot of times they leave that valve hanging I've got one or two here I have no idea that they were a fail item but I guess now that I drive the cars a little bit I get to read more about that.
     
  7. ChapmanF

    ChapmanF Senior Member

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    If I bought a used valve I would definitely pop it open and check the ski jump before using it.
     
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  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    By the time you get P0401 you've likely had no EGR flow to cylinder one (and maybe two) for a protracted time, due to to the uneven progression of carbon clogging of the small EGR passages in the intake manifold.
     
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  9. Johhhn

    Johhhn Junior Member

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    165K or so :(

    engine coolant good.. it shaked *once* on a cold start earlier this year. I do lose about a quart of oil every tank, fwiw.

    Cleanable yes-- but time is precious in getting it back on the road, plus don't want to risk installing a faulty EGR valve.
     
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  10. Johhhn

    Johhhn Junior Member

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    that explains it being slower when it first popped up-- i could feel the timing being pulled, so that's good it does that. thanks!