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2012 Prius just shut down on the freeway; dealer "thinks" "maybe it needs new head gasket for $5400

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by napajan, Jun 7, 2022.

  1. napajan

    napajan Junior Member

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    I was at highway speed and my 2012 Prius just shut down. Would not go back into gear. Displayed multiple warning lights including "Hybrid System Failure." First dealer couldn't find a current problem, only a misfire in the history that caused the engine to shut down. Second dealer (back at home) found elevated coolant system pressure that MAY indicate a leaking head gasket. They also found a rodent-chewed wire that is still intact but shows copper. The car has driven fine with no problems for the past 400 miles since then. They want to change the wire and the head gasket for $5400. I am reluctant to spend that much money when my car is running just fine now! Help!
     
  2. JC91006

    JC91006 Senior Member

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    I can't believe a dealer has to guess at this. You should go to another shop and get another (or a few) estimates/2nd opinion
     
  3. napajan

    napajan Junior Member

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    The first dealer (out of town) had no clue (after a $250 diagnostic). This "guess" was from OUR dealer, after ANOTHER $250 diagnostic. We have not been able to find any non-dealer mechanic with a good reputation who is willing to even look at it.
     
  4. bisco

    bisco cookie crumbler

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    have you had the ipm recall done?

    head gasket is always suspect on a gen 3, but shutting down? i don't think so. how many miles on her?

    what is highway speed, 55? 95? is there movement in the inverter reservoir?

    if you paid the dealers, ask for the trouble codes. if not, get them read
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    ^ This. Almost the simplest way to diagnose 3rd gen head gasket failure.
     
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  6. rjparker

    rjparker Tu Humilde Sirviente

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    It could have shutdown from severe and repeated misfires. Head gaskets are getting as common as flat tires on these cars but the early indication is a severe cold start metal to metal rattle and shake that clears in five or ten seconds and then runs fine. Much later it progresses to a severe rattle during normal start stop engine operations.

    Any loss of coolant level?

    Did anyone use a coolant sealer?

    It would help if you indicated how the first dealer got the car running.
     
  7. napajan

    napajan Junior Member

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    She has 99k miles on the engine, which has been well-serviced. There was NO shuddering, shaking, rattling, or any other indication of a problem before the warning lights came on and engine shut down while I was cruising on I-5 at about 68mph. I pulled over, stopped the engine and read the manual for a few minutes. The car started right back up but all the warnings came on again, and when I turned it off THAT TIME the car bucked before shutting off. I didn't try it again. That is the only time I am aware of that I felt a misfire. The car sat for 2 days before being towed to the 1st dealer. They said it started right up for them but they were able to see the shutoff in the history. They saw rodent damage but no wiring chewed through. The second dealer (I made it home 250 miles with no problems at all) found no obvious problems except "high pressure in the cooling system." They are guessing head gasket. But it starts from cold like a new car, and nothing abnormal at all has happened in the 150 miles I have driven around town since then. The hybrid battery is at 75%.
     
    #7 napajan, Jun 7, 2022
    Last edited: Jun 7, 2022
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  8. PriusCamper

    PriusCamper Senior Member

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    Gotta love Toyota Stealerships these days, it's like of bunch of blind people all standing around an elephant describing different parts of it thinking they're right and everyone else is wrong.
     
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  9. napajan

    napajan Junior Member

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    I have all servicing done at the dealer, so I don't know about a "coolant sealer." Don't know what that is. I am not sure how to measure coolant level.
     
  10. napajan

    napajan Junior Member

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    Thanks, but I don't know what the ipm recall is. I bought this car from the dealer and they have done all the servicing. I think if there had been a recall it would have been done. (I certainly hope so!) I reviewed my paperwork and can't find the trouble codes but they told me the engine misfired and that caused a sequence of events resulting in shutdown. I have looked at symptoms of head gasket failure online and it seems I would be seeing knocks, rough running, rough starting, or SOMETHING if that were the problem I am not seeing anything wrong in the past 2 weeks; she's purring like a kitten. Could the chewed wire have done this?


    I don't understand "movement in the inverter reservoir." What is that, please? And should I be seeing movement, or not? And how to see that? Thanks. Pretty steep learning curve here for me.
     
    #10 napajan, Jun 7, 2022
    Last edited by a moderator: Jun 8, 2022
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  11. rjparker

    rjparker Tu Humilde Sirviente

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    prius busted Head Gasket.jpg
     
  12. napajan

    napajan Junior Member

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    Please tell me what you mean in words. If you think it's the head gasket, why does it not have any indications of that upon cold start or anytime else? Shouldn't I see something? Purrs like a kitten the last 400 miles.
     
  13. JC91006

    JC91006 Senior Member

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    What part of CA are you in?

    At 99K miles there shouldn't really be any problems with the car. It's still considered low mileage for a Prius. Since the car has been running fine for 400 miles, I would just drive it and wait for the problem to come up again. No use throwing money at the problem when it doesn't exist anymore.

    What services have you done on the car? I had a friend with a mysterious hybrid warning that kept coming on, over and over again. The dealer couldn't figure it out. Then one day a really bad misfire, end result was whoever replaced the spark plugs didn't tighten them properly and everything was fine after he replaced all the spark plugs and coils (car had 120k miles)
     
  14. rjparker

    rjparker Tu Humilde Sirviente

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    Telling us were you live can help direct you to a shop. Informing us on the known history helps as well. How long have you owned the car?

    Its 100% you need repairs and whatever happened will recur. The rodent damage must be fixed and steps to eliminate rodents must happen.

    Ipm is shorthand for the Hybrid Power Inverter. It fails on these cars and has a free extended warranty if defined codes occur. Not misfire codes.

    Some Codes were present at least for the first dealer if it shutdown with lights. However they seem to have been non specific misfire codes. Several reasons can cause them but most of the bad plug or coil issues will rapidly repeat or continue. Not so with the all too common head gasket issue. I could tell you it was a fluke but 99% it was not.

    Head gaskets can go weeks between problems at first and that includes no shakes or coolant loss. It is unlikely it had elevated coolant pressure but high coolant temperature is common when a water pump fails. If it had any coolant issues, they must be fixed.

    There are two coolant systems, one for the engine, left side as you look from the front, and one for the Inverter, right side. Both will have movement visible using a strong light when warmed up. The engine coolant may require driving with ac for ten minutes to warm up.

    In reality most of the advice here is aimed at the informed Prius do it yourself person. No one goes from zero hybrid knowledge to diy diagnostics and repairs quickly. A problem with a lack of knowledge is information is not basic enough when quickly given by a mechanic. At a dealer, you are usually getting info second hand through the service advisor.

    In Southern Calif and the Bay Area there are good independent shops like Hybrid Pit or Gasketmasters. Some do it yourselfers here will tell you to buy scanners, use the Dr Prius app with a bluetooth scanner or go back to an experienced shop. I say shop. As is, you can drive it until it does it again but we know there are problems.
     
    #14 rjparker, Jun 8, 2022
    Last edited: Jun 8, 2022
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  15. bisco

    bisco cookie crumbler

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    a chewed wire could certainly bring the car to a stop, depending on the wire, if it grounded itself.

    find the inverter reservoir in your o/m, or google for youtube description.

    start the car and wait for the engine to shut down after warm up so there's no vibration.

    remove the reservoir cap and see if the is any movement in the fluid. movement tells you the pump is working properly.
    no movement tells you it needs to be replaced.
     
  16. napajan

    napajan Junior Member

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    Anyone else have any ideas about what it could be? The chewed wire? something else? I drive long distances, sometimes alone, and need to make sure my car is as reliable as possible. That said, I don't want to do expensive "repairs" that aren't really the problem.....Thanks!
     
  17. napajan

    napajan Junior Member

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    Thanks!!
     
  18. napajan

    napajan Junior Member

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    I am in Napa. A referral to a trusted independent shop would be appreciated. Thanks for all the information!
     
  19. bisco

    bisco cookie crumbler

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    arts automotive and luscious garage
     
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  20. rjparker

    rjparker Tu Humilde Sirviente

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    And Gasketmasters. How long have you had the car? Scammers are flipping cars.
     
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