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Constant MIL and loss of heat

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by lindsmb22, Jan 17, 2011.

  1. lindsmb22

    lindsmb22 New Member

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    Hello All,
    I have a 2009 Prius with 40,000 miles on it. I bought the car used in late November. Recently, my malfunction indicator lamp has been turning on and off and back on. After reading very helpful posts from this website, I topped off my gas tank and made sure to tighten my gas cap. The lamp went off and returned a few days later. Went off again. No strange noises or other issues were happening. My gas mileage has decreased consistently since November, but I realize it's winter. (It's around 49 MPG)
    Yesterday night, while driving to dinner, had the heat cranked (I live in Florida but it's been in the 30's at night). I parked the car and had dinner. On the way home, the heat did not work and surprise, the MIL was back on. Heat hasn't worked today either even giving the car ample time to heat up.
    I checked my fluids, and the pink fluid is "kinda" low and same goes for what I think is another coolant (the reservior to the top driver side that raises a red indicator with volume.)
    I'm having it looked at tomorrow at the nearby dealership. I don't want to be given the runaround nor do I want to go through guess and check process. Other threads have shown similar issues and replacing gas tanks etc. unnecessarily. Could my 2009 be having the same pump issue that was recalled on the 2004-2007s?
    For future reference, is it ok to add coolants on my own without bleeding the line and without risk of air being stuck in there? Can I purchase Toyota quality coolant elsewhere than a dealership?

    Thank you for your help, all.
     
    #1 lindsmb22, Jan 17, 2011
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. The inverter coolant pump is the subject of the recent recall.

    2. The lack of cabin heat points to possible air in the engine coolant loop, which is a separate system vs. the inverter coolant loop. Or, maybe the valve in the engine coolant loop which routes coolant to the heater core and the coolant heat recovery system canister is stuck.

    3. If you add coolant in a timely manner (i.e., before the level drops down so low that air enters the system) then you don't have to worry about bleeding the air out. However if the coolant is allowed to get low enough so that there is air in the cooling system lines then you will need to observe a bleeding process.

    4. You can only purchase Toyota Super Long Life Coolant at a Toyota dealer's parts counter, and this will cost ~$21 per US gallon (already mixed with 50% distilled water.)

    5. If your reference to "malfunction indicator lamp" means the amber-colored engine icon, that would add weight to my guess that the engine coolant valve mentioned in #2 above is bad.
     
    #2 Patrick Wong, Jan 17, 2011
  3. Hal W

    Hal W New Member

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    This coolant valve you talk about Patrick, is this actually the thermostat that controls the water temperature or that controls something else? H
     
    #3 Hal W, Jan 17, 2011
  4. Rokeby

    Rokeby Member

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    #4 Rokeby, Jan 17, 2011
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    No, this is not the engine thermostat. The valve in question is controlled by the engine ECU and is part of the coolant heat recovery system found in North American 2G Prius only. The valve routes engine coolant to the heater core and to the CHRS canister.

    Although it is possible that the OP's car may need a new 12V battery, I would say this is not indicated by the described symptoms.
     
    #5 Patrick Wong, Jan 17, 2011
    1 person likes this.
  6. lindsmb22

    lindsmb22 New Member

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    Wow, my sincere thanks for the quick responses. Patrick thank you for being very clear, I will post back after the diagnosis at the dealership tomorrow.
    Yes, I tested my battery earlier today using the method described in that post. I registered 11.8-11.9 after being parked overnight and I thought that seemed ok.
     
    #6 lindsmb22, Jan 17, 2011
  7. Rokeby

    Rokeby Member

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    What you have there is a weak 12V battery. It shouldn't be due to its
    age, ~4 yr service life is typical. Who knows what happened with the
    previous owner? Deeply discharging the battery due lights left on
    overnight is the beginning of a long, slow slide downward.

    "12V" is somewhat misleading. It's really a 11-13V battery. When the
    held charge is above 12.5, the battery is healthy and reliable. At less
    than 12V, the battery can hold less than half its capacity. It's hurtin',
    and you will be too if gets stressed under heavy load like headlights,
    for lights, defroster resistance heater, fan, etc all at once. And it
    recharges really slowly when the car is running... hours and hours, so
    short daily drives, 10-20 minutes or so, don't help.

    The engine coolant valve pointed out by Patrick is surely the larger
    issue. But as to the 12V battery, if it were me, I'd be looking to get
    a new battery, sooner rather than later.
     
    #7 Rokeby, Jan 18, 2011
  8. lindsmb22

    lindsmb22 New Member

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    Wow, I didn't realize that the small variation down to 11.8-11.9V constituted a weak battery, thank you. I will look into getting one soon. Are they expensive and should I have the dealership do that? They charge a ridiculous $98 diagnostic/visit fee. If the headlights are left in the ON position overnight does that discharge the battery even though they automatically go off when you turn to car off?
     
    #8 lindsmb22, Jan 19, 2011
  9. lindsmb22

    lindsmb22 New Member

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    The problem was indeed a valve in the coolant system.
    Code was P1121.
    I was charged $101.20 for labor (Replaced waterpump is listed by labor but I wasn't charged for one in my parts description.)
    Charged $72.01 for 'Water Valve Assy' part number 16670-21010
    Charged $19.76 for super long life coolant.

    All together, two hours and right under $200. Thankfully, the company to sold me my car gave me a complimentary Fideilty warranty good for 2,000 miles.

    Thank you all for your help and I will get a battery soon.
     
    #9 lindsmb22, Jan 19, 2011
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