EGR valve/check engine light/inspection

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Krall, Apr 8, 2021.

  1. Krall

    Krall Junior Member

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    So bit of a conundrum...

    2010 Prius, 270k, burns about a quart a week (sometimes less) during mostly highway driving.

    I know it needs the EGR valve replaced as check engine light is on, but from reading on these forums many times it's advisable to clean the EGR circuit too. The dealer looks at me funny when I ask for this.

    I took it to a local mechanic and they won't do it either saying I'm just wasting my money replacing it as the oil buring (probably through the rings?) is just going to gum up the EGR issue and cause the check engine light to come on again.

    Anyway, my inspection is past due. I thought the local mechanic had inspected it, but after a brief argument I got the repeated story of it's a waste of money, buy a new engine.

    Could anyone please confirm if I do spend $700 on the EGR valve if the same problem will arise? I'm not against replacing the engine....but just not today :)

    Thanks!
     
  2. Grit

    Grit Senior Member

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    o_O
     
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  3. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    How many miles in a typical week?

    In your shoes, and assuming runaway oil consumption:

    Pull the engine, remove the head and send to a good machine shop for a thorough check over and cleaning, around $500. Supply them with the relevant gaskets and seals from the Toyota gasket rebuild kit, which goes for aroun $200, includes head gasket and pretty much everything, all seals and gaskets in the engine.

    puchase a new short block, around $2000.

    reassemble short block with head, new head gasket and new head bolts (around $200 for a set).

    DIY clean the intake manifold, and all Exhaust Gas Recirculation components, cost being just a few cleaners, rags and brushes. More info:


    Bad Flywheel | PriusChat

    reinstall engine, egr components and intake.
     
    #3 Mendel Leisk, Apr 8, 2021
    Last edited: Apr 8, 2021
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  4. ChapmanF

    ChapmanF Senior Member

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    Have you pulled, or had somebody pull, the trouble codes yet to find out why the check engine light is on?

    EGR problems are only one of many reasons that light can come on, and even if it's EGR problems for sure, the EGR valve is only one possible reason for those.

    The only thing that would be more of a bummer than spending a pile of dough on an EGR valve would be doing that and then finding out the light was on for some entirely unrelated reason.
     
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  5. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Especially spending $700 USD on an egr valve. I believe street price is around $200?

    and there’s an outside chance the Exhaust Gas Recirculation components are all still viable, just need intensive cleaning. Ditto for the intake. At 270 miles, it needs cleaning.

    still runaway oil consumption is probably the elephant in the room??
     
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  6. Krall

    Krall Junior Member

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    Maybe I am misremembering. It might have been $500, but it was a 'new design' updated EGR valve with the pipe. But not the cooler and anything else with the circuit.

    About 100 miles per day so 600 a week. Sometimes more sometimes less.

    It's $700 to pull the engine, otherwise I would LOVE to do that. The service places around here consider engines today 'toys' and 'throw always' when you point out if that were the case I wouldn't have 270k on it they just shrug. Let's just say I'm not in a rebuild friendly location.

    I'll have to look at the DIY cleaning. I'm handy enough to do it, but that engine is pretty packed in the bay.

    Initially the muffler shop pulled the code, but they don't do that kind of work so it went to the dealer who pulled the code and also said EGR valve. Then brought it to a local mechanic who said the same thing.

    Are you saying Toyota's are like Chevy's in that the code doesn't always indicate the problem? I've been down that road many times :(
     
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  7. Krall

    Krall Junior Member

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    Right, but is the oil consumption going to keep killing the EGR valve?

    What's a bit weird is the EGR check engine light just came on within 3k miles, but it's been burning oil for years.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Well, (a) that's not just a Chevy thing by any means, and (b) you still haven't even told us what code you had.

    So there are about 108 different codes the ECM can set. Two of those have anything to do with the EGR system.

    So let's assume you had either P0401 or P0403.

    There are lists of close-to-useless "fortune cookies" that you can look up for each code. The one for P0401 says "Exhaust Gas Recirculation Flow Insufficient Detected" and the one for P0403 says "Exhaust Gas Recirculation Control Circuit".

    You'll notice that neither one of those says "You Need To Replace The EGR Valve". In fact, really neither one of them even gives you any usable detail about what made the ECM set that code, which is why we call them fortune cookies and close-to-useless.

    To find out what either one of them really means, you have to turn to the repair manual (more info), where you find there is a section for each possible code, and every section starts with a box containing the "detection condition" for the code, and that's where you learn what the code is, in fact, telling you.

    So if you look up P0401, you find out that from time to time, while you are decelerating, the ECM sneaks open the EGR valve a little bit, and watches for a pressure sensor in the manifold to show the pressure went up by at least 1 kPa, and that proves that EGR is flowing, and if that pressure change isn't seen, and that happens in two consecutive trips, then something is keeping the EGR from flowing, and the code is set.

    Does that mean the EGR valve is bad? No, there's no way the ECM can know that. All it knows is it conducted a test for end-to-end EGR flow and the expected amount of flow wasn't sensed. Could that be because the valve is bad? Sure, but it could also mean that anywhere in the whole EGR system something is clogged, or it could even mean that the EGR system is just fine but the MAP sensor is bad and that's why the expected result wasn't sensed. The ECM is just a computer trapped in a box; it can tell you exactly what it saw, but it has no way to climb out of its box and poke at things to find out why it saw that. A human has to do that part.

    Same thing with the P0403. The manual will tell you that the ECM saw an unexpectedly low voltage on one of its EGR valve driving terminals, so it thinks there is probably an open or short circuit out there somewhere. Could that mean a problem with the valve itself? Well, yes, but that's hardly likely; there's nothing in there but two center-tapped coils of wire potted in hard plastic. Could there be some corrosion of the pins where the car's wiring plugs into the valve? Did a mouse chew through a wire? Both of those are probably more likely.

    Again, the only real use you can make of trouble codes is to find out what they tell you the computer saw. Then you (or whoever is doing the diagnosis) must ask: (1) what are the possible circumstances that could make the computer see that? and (2) what tests would help me determine which of those is the real explanation?

    Then the human has to do that work. If the result of that testing shows the problem to be a bad valve, then you change the valve. If it shows the problem to be something else, you deal with the something else.

    So the reason it's not just a Chevy issue is that there's no getting around it: a code can never be telling you anything except what a computer in the car did or did not sense, because that's the only thing any computer in the car is able to tell you. It's always up to the human to take that information, form the right questions about why the computer did or didn't sense that, and find a way to answer them.
     
  9. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Exhaust Gas Recirculation clogging will happen, regardless of engine oil consumption. It should be dealt with by 100k miles, both the EGR components and the intake, which is the final leg of the Exhaust Gas Recirculation gas journey. At 270k miles..., it will be very clogged.
     
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  10. Krall

    Krall Junior Member

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    Thanks for taking the time to write that up and inject some humor! I'm going to print it out as a reference guide ;) I was sort of joking with the Chevy reference as every time I get a code for the EVAP it ends up being a wild goose chase at the mechanics shop.

    I was looking for my dealer receipt with the codes and diagnostic info, but I didn't locate it yet. I want to say they said the EGR valve was stuck open.

    Anyway once I find that I'll post it. I did use my code reader and I got: P0401, P0420

    So basically I need to unclog it...

    I see on ebay I can get a OEM EGR pipe w/cooler for $300 & the EGR valve with gaskets for $200. I was thinking of going this route as on here I've read it's not so easy to remove the carbon deposits and at 270k I'm not so sure disassembly of anything will be easy lol
     
    #10 Krall, Apr 9, 2021
    Last edited: Apr 9, 2021
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  11. AW82

    AW82 Member

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    Sounds like OP isn't the diy type, otherwise, what's the going price for a 2015 engine these days? I think I've seen less than $2k on here. Even less if you're willing to do a gen4 swap. With those miles and the oil consumption, a swap sounds like the smarter direction if you can diy.
     
  12. ChapmanF

    ChapmanF Senior Member

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    You might see if your code reader is able to pull up "mode 6" test results (they might call it something else), and post what it's actually showing for the EGR flow test, as you can see in this thread. That would show how low the flow is.

    There are further tests that can be done to try to further pin down just what's going on, but those require Techstream.

    Given that P0401 is an insufficient flow code, it's hard to square that with the shop telling you they thought the valve was stuck open. I have a feeling they didn't put as much effort into that diagnosis as they could have.
     
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  13. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Valve could be stuck open (and maybe just a big carbon traffic jam) and the Exhaust Gas Recirculation passages in the intake completely carbon-bunged. At 270k it’s probable.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    Yes, that could be an explanation for an otherwise counter-intuitive diagnosis "your insufficient-flow code is because your valve is stuck open".

    The question is, is it likely the shop did any of the necessary manual labor to establish that's the case, or just look at a reported DTC and say something the DTC by itself does not support?

    Regrettably, both things happen (sometimes depending on the shop). A lot of bogus statements of what DTCs mean get bandied about with some regularity.

    The labor for them to have actually found out "yeah, the insufficient flow because it's stuck open and clogged" would probably have taken fifteen minutes at a minimum—thinking about it, you could confirm stuck-open just by removing the stator from the valve. (To confirm it's well closed, you'd have to feel the rotor spin down to its positive stop and then also confirm you can still push it about 3/4 mm against the spring without moving the stem, as the threads give it about that much end play.)

    So the OP may be able to tell whether they did that based simply on how long the visit lasted before they came back with their diagnosis.
     
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  15. Krall

    Krall Junior Member

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    Bite your tongue :) I'm pretty handy, but time is limited because I'm self employed and I know a car with 270k that lives in the North East is not going to be easy to disassemble. That said a DIY engine swap is not in my future unless it's to work on my '56 Chevy.

    It's a pretty basic reader so I doubt it has "mode 6", but it looks like I just need a Techstream cable to run it from my laptop?

    I don't know how much effort the dealer put in, but I know the 'local mechanic' put in zero.

    Would clearing the P0420 code with some catalytic converter cleaner help out?

    From a logical standpoint it seems likely that my EGR pipes are clogged, my catalytic converter is drowning in oil from the burn off situation and I should just get some catalytic converter cleaner, BG 44k/MOA/EPR and either clean my pipes or replace them.
     
    #15 Krall, Apr 9, 2021
    Last edited: Apr 9, 2021
  16. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    With the Exhaust Gas Recirculation cooler a series of soaks with hot/concentrated oxi-clean solution “may” redeem it.

    Easiest way is to stopper one end and fill: stopper with small/large taper of 19/26 (mm) and length 28 “might” be what I used to facilitate process; my Amazon order history indicates that. But if possible verify what’s needed.

    Also, it may be so carbon-socked that you need to clear at least some of the passages mechanically, say with a wire on dremel, or drill set to low speed.
     
    #16 Mendel Leisk, Apr 9, 2021
    Last edited: Apr 9, 2021
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  17. Krall

    Krall Junior Member

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    I'm having a hard time picturing this. You guys say it's probably plugged/clogged, but when I think of carbon build up I think of a pan that's been over heated way too much. I did just watch a video where a guy used what looked like a pipe cleaner to mechanically remove the build up first before going on to carb cleaner.

    Does the pipe part #25610 also become clogged?

    EXHAUST GAS RECIRCULATION SYSTEM. Toyota Prius | Toyota


    I'm really thinking of just getting that, #25620 EGR #25601L Cooler off ebay and taking mine off and cleaning them for a spare. Is there any benefit from getting them off a new Prius?
     
  18. Grit

    Grit Senior Member

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    there is a thread in this sub forum that’s 200 pages long that covers this single topic, read that and know how to tackle the task one time, or if you have time rediscover everything we’ve covered in the 200 pages.
     
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  19. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Everything clogs. At 270k miles the cooler will be pretty much a chunk of anthracite coal. Ditto for the valve, at least the seat zone. The pipe between valve and intake manifold will be maybe 50% volume reduced. The small EGR passages in intake are likely completely carbon bunged, first and foremost at cyl 1 (passenger end).
    Info and links:

    Bad Flywheel | PriusChat
     
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  20. ChapmanF

    ChapmanF Senior Member

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    Even before buying anything, you might learn something quickly by removing the black stator from the valve (2 Phillips-head screws, tend to be stubborn), spinning the rotor inside counterclockwise off the valve stem, and seeing whether the stem pushes inward easily and returns outward to you on its spring. Turning the rotor around and looking in the end, you can see if the ski jump on the inside is intact.

    [​IMG]
     
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