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Water Coolant Valve/ Oil Temp Sensor part of Powertrain???

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by daisy555, Aug 12, 2017.

  1. daisy555

    daisy555 Senior Member

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    Hello!
    It's been a while since I've posted. CT attorney general's office finally received a response from Toyota Corp. Toyota is stating water coolant valve and oil temp sensor are part of the powertrain. Please help me understand this. CA dealerships consider these parts part of the emissions.

    Otherwise my 2009 Prius still has a small chug a lug sensation sometimes when idling at stop light or if I've just started car but pause a bit before driving off. I hope to duplicate it at next oil change.

    Thanks!
    Maria
     
  2. Kevin_Denver

    Kevin_Denver Active Member

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    By the "water coolant valve", do you mean the thermostat? The thermostat keeps water from flowing to the radiator until a certain temperature is reached, allowing faster engine warmup. This faster engine warmup increases fuel economy, reduces emissions, and increases engine life (by reducing deposits and wear). It's really part of both emissions control and the powertrain. I see both points of view.

    The oil temperature sensor is one input to the car's ECU (computer) and its data may be used with the rest of the sensors to determine air fuel ratios and engine timing, which affects emissions. However a major function of this sensor is to detect engine overheating to protect the powertrain. It's primary function is not related to emissions, so I would call this a powertrain part.

    Both of these parts are in virtually all other cars on the road today and function the same in the Prius, so I would think that the laws applying to all other cars would be the same for the Prius.

    To answer your other question: A little rough engine running is not rare when the engine is cold and just started. Also when the car transitions from stage 3 to stage 4 (see this), the engine ECU performs some tests on the engine for 5-10 seconds (only Toytota knows exactly - most likely testing limits of ignition timing) at idle before stopping it with an intentional harsh shutdown to indicate this transition. During the testing, some rough engine running is expected. If your check engine light isn't on, most likely everything is okay. The Prius is very good at reporting engine problems via the check engine light.
     
  3. bisco

    bisco cookie crumbler

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    how many miles on him?
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It might help if you give us a little background about the issue that concerns you. The California warranty is based upon specific California laws governing the sale of motor vehicles. Since you are not in California you can't expect to benefit from the warranty which Toyota extends to owners in that state.

    The Prius does not have an oil temperature sensor, or oil level sensor.

    The powertrain includes the engine. The engine coolant valve supports the engine. Hence a reasonable case might be made that the engine coolant valve is part of the powertrain. The powertrain warranty is typically very specific about what is included and excluded.

    The engine produces noxious emissions and the engine coolant valve helps to reduce those emissions. Hence it is reasonable to consider that valve part of the emissions control system. I hope you can understand that it is not obvious that the valve belongs in one bucket or the other.

    In any event, the engine coolant valve is not a particularly expensive part, so I hope you are not losing sleep over this. The car is 8 years old, after all.
     
  5. daisy555

    daisy555 Senior Member

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    Thanks for your responses. I skipped some details because I had spelled them out at an earlier date and wasn't sure if I should ask these questions on old post or start new.

    Back when I was dealing with repair (and losing sleep over it because I was given multiple conflicting answers by dealerships), CA dealerships were telling me they cover these parts under CA emissions warranty. My car has CA emissions warranty because it was originally purchased and now registered in state (CT) that honors CA emissions warranty. Maybe these CA dealerships were covering it when they shouldn't have been. They even confirmed with vin #.

    Under CA emissions "performance" warranty, Prius manual states Toyota has to make repairs if car isn't passing emissions test. Emissions tester in CA and CT said car wouldn't pass test if engine light was on and these parts were failing. Prius presently has 116,000 miles on it. CA emissions warranty is for 150,000 miles or 10 yrs. Same for hybrid battery I think. Sorry it's late and I got a flat tire in the blazing heat today so I'm not thinking clearly.

    Maybe parts aren't expensive but labor is and I can only do basic air filter changes myself. I can't afford to pay for repairs that are covered under warranty. I was initially quoted about $800 total. Toyota has reimbursed me but I was asking question so I could better understand their logic. The wording of the emissions performance warranty is very misleading.

    Thanks again.
     
  6. daisy555

    daisy555 Senior Member

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    Hi Patrick I explained situation regarding CA emissions warranty in my previous post. My 2009 Prius apparently has an oil temp sensor since they did replaced it. I do get what you are saying about the coolant valve. I was expecting coolant valve to be covered under emissions warranty because it's being covered in CA. My Prius supposedly has the CA emissions warranty per Toyota Corp which means I have the same warranty whether in CA or CT since CT honors CA emissions warranty.

    Thanks for your help.
     
  7. Kevin_Denver

    Kevin_Denver Active Member

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    Glad to help! Note that in many states (Colorado for example, can't speak for others), if the check engine light is on for any reason (OBD code is set), the car will not pass emissions (even if the code is set for something not emissions related). In Colorado, they don't even check the tailpipe emissions for the Prius; they just plug in an OBD cable and check that there are no codes. Ridiculous you have to pay $25 just for them to do this.

    I believe in California Toyota is required to pay for the repairs if you fail the tailpipe emissions part of the test (CO, nitrous oxides, particulate limits, etc), not failing due to an OBD code being set.
     
  8. daisy555

    daisy555 Senior Member

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    CT is the same situation. Yes, ridiculous it is. BTW the chug a lug sensation....someone had mentioned as miles increase this sensation can become more noticeable. Maybe that's what has happened although it's quite startling to have the car actually make a jerking movement while I'm siting in parking lot or have gotten out of car to get something out of back seat. This does not seem right but no engine light on so I've been letting it go for now. I like to catch things before they become a crisis due to my tight budget. Couldn't duplicate for mechanic last time but I think I'll be able to next time. Thanks again!
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Thanks for providing the background to your story.

    Regarding the jerking motion when parked, do you set the parking brake? If not, I recommend that practice.
     
  10. daisy555

    daisy555 Senior Member

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    Trying to decide whether to go to dealership for diagnostic while getting cheap oil change or take it to independent mechanic (same labor costs) who has been hybrid trained. He was able to diagnose a noise under front of car that dealership didn't even notice. I thought my shocks were starting to go on left front side : } and it was the heat shield or whatever that big black plastic piece is under front of car. It needs to be replaced or reattached. Clips broke off in one area.
     
  11. daisy555

    daisy555 Senior Member

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    Good idea! I never set it because everything is flat around here. Anytime I've used it I forget to release it. : } Need to put a post it up or something. Thanks!
     
  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Please provide the part number and description from your repair invoice, thanks.
     
  13. bisco

    bisco cookie crumbler

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    how many miles on her?
     
  14. daisy555

    daisy555 Senior Member

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    Hi Bisco...116,000. Remember me with the record breaking posts when I was buying this car?? : )

    Help!!!
    I'm searching posts for tire recommendations but tires are no longer available per tire store. I'm on my old iPhone and don't see area for posting new post here so I'm asking hoping someone sees this. I live in CT and need all season since I can't afford snow tires. Flat can't be repaired. : (

    Thanks!
     
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  15. Kevin_Denver

    Kevin_Denver Active Member

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    Daisy, look at Continental TrueContact tires. They have very good snow and wet handling for an all season while maintaining good fuel economy. See the ratings at Tire Rack: Standard Touring All-Season Ratings
     
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  16. daisy555

    daisy555 Senior Member

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    Thanks, Kevin. I will look them up right now. Any thoughts on Michelin Defender? Thanks so much!

    Never mind...I just looked at chart and saw that defender doesn't perform as well. Thanks!
     
  17. Kevin_Denver

    Kevin_Denver Active Member

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    Not nearly as good in the snow. 6.1 rating at Tire Rack versus 8.1 for the True Contacts, also fuel economy is a bit worse I think too, but I believe it has a better tread life.
     
  18. daisy555

    daisy555 Senior Member

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    Just read through some reviews. Both brands have issues but I wouldn't buy Michelin Defender after reading reviews. Continental not good on ice which is my biggest fear having been in a bad 360 spin as a youngster. I don't understand why there isn't a tire company that makes an all around great tire. I've used General Altimax several times not by choice. Wouldn't buy again due to tread life. None of these tires last anywhere near the rated mileage.
     
    #18 daisy555, Aug 14, 2017
    Last edited: Aug 14, 2017
  19. Kevin_Denver

    Kevin_Denver Active Member

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    Basically it's not possible from an engineering standpoint. Soft compounds grip better in winter but wear rapidly in summer, more tread pattern increases grip in snow and wet but worsens fuel economy. Only winter tires, especially studded will have okay grip on solid ice. Everything else will be marginal to terrible.
     
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  20. daisy555

    daisy555 Senior Member

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    Well...that makes sense. : ) Wish I could afford winter tires. Maybe some day. I'm home and posted my tire question as a new post. I really appreciate you explaining the reasons behind all of this. My brain really likes to know why. : ) Thanks