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High Coolant Temp Warning Flash Then Off

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by Kenneth S, May 15, 2024.

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  1. Kenneth S

    Kenneth S Junior Member

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    Driving on the highway I noticed the High Coolant Temperature warning light flashing for a few seconds and then turn off. I have only seen this happen this one instance. I had just put the car in Power Mode to quickly accelerate from 45 to 65 mph but then put it back in Eco Mode and was driving at 65 mph. I don't normally switch drive modes and so I of course am wondering if the two events are correlated. Coolant level is fine and holding steady. (I check it about once a month or two.)

    I flushed coolant and transmission fluid at 101,000 miles. No parts were replaced at that time, just fluid.

    Is this a sign that something is about to fail? Is there something else I should check? Or should I wait and see if the warning happens again?

    Thank you all!
     
    #1 Kenneth S, May 15, 2024
  2. xliderider

    xliderider Senior Member

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    It may be a sign that your water pump is starting to go. The impeller usually gets stuck and is the cause of the failure. You could be seeing early signs of the impeller not spinning at sufficient speeds to keep the coolant circulating efficiently.

    SM-G781V ?
     
    #2 xliderider, May 15, 2024
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  3. Brian1954

    Brian1954 Active Member

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    ^ I agree with the post above.

    You should monitor the engine coolant temperature by purchasing an OBD2 bluetooth adapter and use an app. Engine coolant temperature normally does not go above 202F. If it does, you may want to replace the pump.
     
    #3 Brian1954, May 15, 2024
    Last edited: May 15, 2024
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  4. Xterra72

    Xterra72 Senior Member

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    That’s exactly what happened to me.

    Next time it happens, check your engine coolant reservoir. I had signs of coolant spill.

    I replaced the engine water pump and it solved the problem.
     
    #4 Xterra72, May 15, 2024
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    From what I've read here, it'd be prudent to replace the water pump somewhere between 100K~150K miles, even without symptoms. Depending on your risk tolerance, that could be in conjunction with either the first or second engine coolant change, for convenience.

    Aisin WPT-190 is supposedly what Toyota's using, fwiw.
     
    #5 Mendel Leisk, May 16, 2024
  6. Kenneth S

    Kenneth S Junior Member

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    Greetings! Yesterday while driving my 2013 Prius V, I saw the Hot Coolant indicator flash for 2 seconds then come on solid. I heard a sound like pressure releasing, which I later discovered was coolant spewing past the fill valve. The coolant indicator then turned off and the check engine light turned on.

    The only visible issue I see is that coolant sprayed out of the reservoir (the one on the passenger side of the engine compartment). There is still a lot of coolant remaining, just a bit below the Low line. I had not been leaking coolant before this.

    Haven’t figured out yet what the error code is. Curious what you think the problem might be. Thanks!
     
    #6 Kenneth S, Jul 26, 2024 at 8:11 AM
  7. Brian1954

    Brian1954 Active Member

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    This is the same issue as your other thread that you created on May 15th. https://priuschat.com/index.php?posts/3451543
    Have you been monitoring the engine coolant temperature like I suggested in post #3?

    You need to replace the engine water pump ASAP! An OEM water pump is preferred.
     
    #7 Brian1954, Jul 26, 2024 at 9:15 AM
  8. Kenneth S

    Kenneth S Junior Member

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    Codes are for failed water pump, failed thermostat, and shorted temperature gauge. You all were spot on with your assessments!
     
    #8 Kenneth S, Jul 26, 2024 at 10:09 AM
  9. Kenneth S

    Kenneth S Junior Member

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    Yes, I was following your advice and checking the levels a twice a week. That issue did not recur until now when it appears the pump failed
     
    #9 Kenneth S, Jul 26, 2024 at 10:10 AM
  10. Brian1954

    Brian1954 Active Member

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    I did not advise you to check the level twice a week. This is what I advised you to do:
    Can you please tell us what trouble codes were read? The actual trouble code like P261B, etc. not a description of the codes.
     
    #10 Brian1954, Jul 26, 2024 at 11:19 AM
    Last edited: Jul 26, 2024 at 11:28 AM
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  11. Kenneth S

    Kenneth S Junior Member

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    Oh, you’re right. It was a different user who posted after you that recommended to monitor the coolant levels regularly. My mistake.

    I don’t own the device to read error codes. I relied on a service center for that. My hope from the discussions here in PriusChat is to get a second opinion and try to learn from others’ similar experiences. You and the other users rightly tipped me to the water pump. I think the lack of leaking fluids corroborates that conclusion even without knowing the error codes.

    I also see now, if the temperature monitor is shorted or otherwise failed, that it was a mistake to rely upon dash indicators to tell me if the coolant was hot rather than buying the Bluetooth device you recommended.
     
    #11 Kenneth S, Jul 26, 2024 at 12:47 PM
  12. rjparker

    rjparker Tu Humilde Sirviente

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    The problem is driving it since May with an engine that likes to blow head gaskets even without overheating. Overheating is the traditional and easy way to blow a head gasket on any engine.

    Your water pump was probably running slow due to drag or worn impellers. The first alerts were the engine at 248f instead of ~200f or less. The pressure relief cap operating means it went higher.

    My policy is a car is shutdown and towed if necessary when a temperature warning occurs. If it’s an obvious leak, fix it. But these cars rarely have a coolant system leak even in the radiator since the radiator is protected by the AC evaporator coil.
     
    #12 rjparker, Jul 26, 2024 at 1:17 PM
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  13. Tideland Prius

    Tideland Prius Moderator of the North
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    *Threads merged*
     
    #13 Tideland Prius, Jul 26, 2024 at 2:00 PM
  14. Kenneth S

    Kenneth S Junior Member

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    Are you recommending I replace the head gasket along with the water pump?
     
    #14 Kenneth S, Jul 26, 2024 at 2:17 PM
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