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Coolant Thermal Container Pump

Discussion in 'Gen 2 Prius Main Forum' started by Frontporch, Dec 7, 2021.

  1. Frontporch

    Frontporch Member

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    On my 2007, when the pump/valve that cycled coolant into and out of the thermal container went bad I had a check engine light. Does the 2004 also signal a CEL when that pump is no longer working correctly?

    I ask because the 2004 that I picked up seems to have the MPG drop more than expected in cooler weather and I also don't notice a pump running after I shut down. The 2004 does not have a CEL on.
     
    #1 Frontporch, Dec 7, 2021
  2. bisco

    bisco cookie crumbler

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    idk, but would suspect all gen2 have that. it would be required by emission laws i think
     
    #2 bisco, Dec 7, 2021
  3. Frontporch

    Frontporch Member

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    I was under the impression that its more a fuel efficiency thing. Makes the motor run more efficiently right from the start, eliminating the need for a "warm up" by pumping in hot coolant. On my 2007, when the pump went, the general consensus here that I would loose some MPG, but it wasn't important otherwise. In NJ I eventually had to replace the pump/valve because any CEL will cause you to fail the inspection. Ironic to fail for a part that almost every other car doesn't even have.
     
    #3 Frontporch, Dec 7, 2021
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  4. bisco

    bisco cookie crumbler

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    i thought cel's were always emission related, my bad
     
    #4 bisco, Dec 7, 2021
  5. Georgina Rudkus

    Georgina Rudkus Senior Member

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    The thermos was replaced in the Gen 3 and above with the exhaust pre-heater. It serves to make heat available to the car when the engine is not running or prior to engine warm up .

    Yes, it is calculated into the EPA's calculations for the emissions system.
     
    #5 Georgina Rudkus, Dec 7, 2021
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  6. Frontporch

    Frontporch Member

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    Interesting. I was thinking about this the wrong way
    Maybe that pump is working. I need to take a closer listen or maybe feel for heat by the hoses
     
    #6 Frontporch, Dec 7, 2021
  7. Tombukt2

    Tombukt2 Senior Member

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    My pump went out in winter got the light . Hoses cold all time Until I get on hiway. Then inverter 125 degrees all hoses 80 ish no coolant moves . Radiator normal hose temps top n bottom . Drove like this a week in town mostly. Code on for this pump replaced pump code gone . Light off . Mpg stayed at 44 but I noticed reduced inverter charging possibly never saw green without pump?... Pump working I see green every few days.

    SM-A715F ?
     
    #7 Tombukt2, Dec 8, 2021
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  8. nancytheprius

    nancytheprius Active Member

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    @Tombukt2 the car's goal is to actually be blue (60% SOC) for longevity. Green is typically from regenerative braking, but the full charge green isn't actually what you always want
     
    #8 nancytheprius, Dec 8, 2021
  9. Tombukt2

    Tombukt2 Senior Member

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    Yes I gathered I wasn't supposed to see green very much but it's actually quite rarely and it doesn't seem when I'm breaking it seems like it's when I'm going down the highway at like 62 miles an hour just cruising along and I will look over and all of a sudden it will be green stay that way for about 3 minutes at the same cruising I haven't changed the thing and then it'll revert back to blue and there's always a white line above whatever color is showing well maybe not the purple but so in the blue I always have a sliver of white showing at the very top of the battery logo it never fills all the way. But the cars running great and generally I'm getting 43 to 47 driving the HELL out of the car

    SM-A715F ?
     
    #9 Tombukt2, Dec 8, 2021
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  10. mr_guy_mann

    mr_guy_mann Senior Member

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    The CEL is always emissions. For emissions, of emissions, by emissions, so help me federal EPA.

    Posted via the PriusChat mobile app.
     
    #10 mr_guy_mann, Dec 8, 2021
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    Best way I know to check the pump is to connect to the ECM with Techstream (or similar capable scantool) and look at engine data while the car is in ON but not READY. Now on a cold engine the ECT (coolant temp) sensor (and the temp sensor for the thermos) should read ambient. When you go to READY (and there is hot coolant in the thermos from the day or two prior), then the temp sensor readings should go up 30-60°F in the time before the ICE starts up.

    Usually if there is a problem with the pump not working then the ECM will set a code.

    Posted via the PriusChat mobile app.
     
    #11 mr_guy_mann, Dec 8, 2021
  12. mr_guy_mann

    mr_guy_mann Senior Member

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    If you can make the engine warm up quicker, then it will produce less emissions during that time. The longer the engine is running below normal operating temperature, the more fuel has to be used to keep running smoothly which equals more emissions.

    Just using less fuel on a cold engine sometimes works, but if it causes poor engine operation (hesitation or misfire) then the feds get upset.

    Posted via the PriusChat mobile app.
     
    #12 mr_guy_mann, Dec 9, 2021
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