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Prius gen4 2018 with 5 codes after emissions pass?

Discussion in 'Gen 4 Prius Main Forum' started by carloz1234, Dec 29, 2023.

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  1. carloz1234

    carloz1234 New Member

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    Own a 2018 Prius Gen 4 with 19K miles. Last week I was driving it and the Engine Light came on. Used a OBD2 reader to read the codes:

    P043E - Evaporative Emissions System Leak Detection reference orifice Low Flow $07E18
    P043F - Evaporative Emission System Leak Detection Reference orifice High Flow $07E18
    P2401 - Evaporative Emission System Leak Detection Pump Control Circuit Low $07E18
    P2402 - Evaporative Emission System Leak Detection Pump Control Circuit High $07E18
    P2419 - Evaporative Emission System Switching Valve Control Circuit Low $07E18

    During this I get an emission notice, so I figure bad timing but lets give it a shot. So I go to the gas station, Fill full tank, tighten gas cap. Drive some 70 miles for about 3 days and Readiness is all green on OBD2 reader. Take it to emissions test center and all passed with no issue. Some days after the engine light came back ON again with same codes P043E, P043F, P2401, P2402, P2419. Obd2 shows 10 drive cycles aprox 3 hrs of drive time since clear codes.

    What could be causing this issue? The gas cap looks good, seal looks good. should I replace the fuel cap? is it more than this?
     
    #1 carloz1234, Dec 29, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    If the Gen 4 does it like Gen 3, those codes aren't set by drive time; they're set upon failure of the evap system self test, which happens when you're not driving, about five hours after you park the car. You can sometimes hear the humming of the little leak-detection pump near the rear of the car around that time.

    Seems like something intermittent is going on, as the test had to pass at least once after your code clear, in order to show readiness. Then after your inspection, it ran again and didn't pass. At least you should have plenty of time to diagnose the issue before the next inspection is needed.

    Or maybe the Gen 4 does it differently. Anybody looked in that part of the Gen 4 repair manual?
     
    #2 ChapmanF, Dec 29, 2023
  3. carloz1234

    carloz1234 New Member

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    I don't hear any humming, drives normal too. What is bizarre is, it had a check engine with same codes, I cleared the codes, drove it some 3 days with 75 miles, every night I let it sit full 10 Hours before starting it, On the 3rd day, all Green lights on obd2 reader -ready for emission test - which it passed with flying colors. I drove it some more and now check engine back on - same codes. If it is the EVAP system itself, does it sit behind the drivers rear wheel ? is it below or above gas tank? Toyota Dealer wanted $200 to diagnose with there reader - even after giving them OBD2 codes over the phone etc. I can swap out the EVAP canister with electric pump motor. I believe its some $400 part for part# 77740-47110 (maybe fit for 2018 Prius 4?), but the question would be where is this EVAP located and how difficult of a task is it.
     
    #3 carloz1234, Dec 29, 2023
    Last edited: Dec 29, 2023
  4. ChapmanF

    ChapmanF Senior Member

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    The evaporative emissions system is complicated and includes a number of components. It is hard to diagnose by guessing. The sections in the repair manual for the codes you have will explain how the system works, how the test works, and how to proceed with troubleshooting.

    Toyota Service Information and Where To Find It | PriusChat
     
    #4 ChapmanF, Dec 29, 2023
  5. FuelMiser

    FuelMiser Senior Member

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    When filling the tank, do you ever top off after the nozzle auto stops? This is a no-no. If too much fuel comes into the filler neck in the car it can mess with the fuel vapor emissions control.

    If those codes keep showing up, you better head to a mechanic to trace down. There is a fuel vapor capture system that runs after the car sits idle for awhile. It makes a soft humming sound that is very easy to miss.
     
    #5 FuelMiser, Dec 30, 2023
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  6. carloz1234

    carloz1234 New Member

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    Is there a FUSE or RELAY that could be bad which runs the EVAP system? Would anyone here know where its located?
     
    #6 carloz1234, Dec 30, 2023
  7. bisco

    bisco cookie crumbler

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    isn't it covered by the 15 year emissions warranty?
     
    #7 bisco, Dec 30, 2023
  8. carloz1234

    carloz1234 New Member

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    Don't I wish it was covered, like most EV Vehicles, it starts costing you more money than its worth in gas savings. Just curious if anyone knows - Is there a EVAP or GAS tube ventilation for this system?
     
    #8 carloz1234, Dec 30, 2023
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Wondering the same thing.
     
    #9 Mendel Leisk, Dec 30, 2023
  10. carloz1234

    carloz1234 New Member

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    I fill it to full once it stops, I use the automatic gas handle till it clicks off.
     
    #10 carloz1234, Dec 30, 2023
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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah that's good. I think it's topping up into the neck that can lead to problems.
     
    #11 Mendel Leisk, Dec 30, 2023
  12. carloz1234

    carloz1234 New Member

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    I'm thinking with such low mileage(20K) it could be the gas cap or seal maybe the cause too(just a guess). Alternately, I could drive the car with half tank of gas to see if the canister elements can dry out on its own in a couple of days to a week - its 35F out here now. Maybe by drying it out, it may return back to normal after several drive cycles.
     
    #12 carloz1234, Dec 30, 2023
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  13. ChapmanF

    ChapmanF Senior Member

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    The vapor capture system is doing its job all the time; the humming sound you sometimes hear when the car is off is only the self-test that the system performs on itself to detect problems. The test works like this (chart from the Gen 3 repair manual, there might be some Gen 4 differences):

    [​IMG]

    The self-test has five steps, A through E, and while the test is happening, the leak detection pump is turned on, as the chart shows, from the start of step B through the end of step E, and that's the sound you hear.

    As you can see, the evap system is complicated. The codes that it can set generally don't indicate something that does or doesn't run because of a fuse; the codes tell you specific results of specific tests that are explained in the repair manual. The manual also explains how to troubleshoot problems. It's a more-than-twenty-five-words business. The manual has the information you need for it.

    Toyota Service Information and Where To Find It | PriusChat
     
    #13 ChapmanF, Dec 30, 2023
  14. carloz1234

    carloz1234 New Member

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    Took it into Toyota Dealer, tech performed Active-Test on Evap system, when Activating the Evap Pump - it does NOT turn ON. Dealer wants $1400 to replace it, the part is $376.50 the rest is labor. How difficult can it be to replace a evap pump/tank ? Also hard to tell, but how can the EVAP system not have a Fuse location listed?
     
    #14 carloz1234, Jan 1, 2024
    Last edited: Jan 1, 2024
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Here's the Evap Emission System excerpt from Repair Manual.

     
    #15 Mendel Leisk, Jan 1, 2024
  16. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    How can it not be covered? Look at the emissions warranty. EV don’t have these evap problems. When you say like most ev’s, it starts costing you more money than gas, is an interesting statement. Yours is having problems with the gas part of the car, right? A person would think a Toyota dealer would be all over a repair the factory pays for. Is it a salvage vehicle or something?
     
    #16 Mr.Vanvandenburg, Jan 1, 2024
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  17. carloz1234

    carloz1234 New Member

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    no, in fact bought new in 2018. I'm also having a hard time believing its evap pump etc. The one thing I cannot find is the FUSE that controls the evap or vsv solenoid. Is there a fuse for this or a shared fuse location- anyone? I want to verify if its blown etc causing all of these issues.
     
    #17 carloz1234, Jan 1, 2024
    Last edited: Jan 1, 2024
  18. Mendel Leisk

    Mendel Leisk Senior Member

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    Maybe verify eligibility for warranty coverage with:

    service department manager
    Another dealership if practical
    Toyota USA
     
    #18 Mendel Leisk, Jan 1, 2024
  19. ChapmanF

    ChapmanF Senior Member

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    Can you get to the repair manual excerpt that Mendel posted in #15?

    That right there should have the answers in it to the questions you've already asked, as well as to the ones you haven't yet realized you need to.
     
    #19 ChapmanF, Jan 1, 2024
  20. carloz1234

    carloz1234 New Member

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    yes got the excerpt, thank you for that. Anyone with experience know if the muffler needs to come off to remove the old Evap canister with pump?
     
    #20 carloz1234, Jan 2, 2024
    Last edited: Jan 2, 2024
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