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Master Warning Light After Coolant Valve Replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by apfiefer, Mar 25, 2023.

  1. apfiefer

    apfiefer New Member

    Joined:
    Mar 25, 2023
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    Location:
    Iowa
    Vehicle:
    2008 Prius
    Model:
    Base
    Hi all,

    I have an 08 base model that has been giving me a lot of trouble with the coolant control valve. I have had to replace it three times due to it freezing in place and not sending coolant to the engine, causing overheating. Our guess is that our usual mechanic was cheaping out on the coolant and it was causing some kind of corrosion or wear.

    After this most recent replacement, the second we have done ourselves, upon starting the car, the master warning is lit up and the engine does not start. There are no check engine error codes listed. We filled up the radiator and the reservoir just as we have before. We did have to unplug the 12v battery for the maintenance, but it has been reconnected.

    Any advice would be appreciated, thank you.
     
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
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    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    You most likely don't have enough coolant. Check the radiator level again after it has cooled down.

    These valves normally don't fail often, you may have other issues with your car. When this valve is stuck, it does not give you the red triangle, it lights up the check engine light.
     
  3. Tombukt2

    Tombukt2 Senior Member

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    Nov 29, 2020
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    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    I would think that three coolant valves being ate up by cheap coolant or by cheaping out on the coolant which would mean exactly what Is it green other than that Dex cool Asian red or whatever. Should net you are running vehicle without eating up everything the mixed cooler touches that sounds well kind of a stretch at best. Maybe they're cheaping out on the coolant valves are you buying used ones or aftermarket dealer replacement some people will say that cheap replacements aren't the way to go because they're not built up to snuff like the inverter pump if you buy an aftermarket one which looks just like the real thing they have skimped on something internally I've busted them apart to look at them I can't see any different circuit boards and everything look very similar but the cheap ones fail as fast as you buy them the one for $130 from the Toyota dealer apparently does not I don't own one so I don't know. I would think with the red Master triangle warning light on you should have codes that someone needs to retrieve to get a starting point.