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Help with P1116

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rposton, Feb 25, 2016.

  1. rposton

    rposton Member

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    Light comes on, I get someone to clear it, it stays off for months then comes on again. I brought it to the attention of the dealer, and he thought the electric pump near the thermos was more noisy than it should, so it was replace, the electric pump, that is, but could not find anything else wrong. The thermos and sensors are one assembly, they say, and you can't buy and replace just parts. That assembly is $1500.00, the dealer says. This has been going on for a few years now, and the car has passed the annual emissions with the light off, so maybe I should purchase one of those code readers instead, and keep checking the code and resetting if need be.

    Off the top of my head, I think I go through this 2 to 3 times a year with this car. It has 483K miles on it now, which is approx. 50K per year since I got it.

    Looking in the top of the radiator, I know that it has two, I never see fluid, so I sometimes I add till I see coolant, which is usually about a cup. About a cup a year. The coolant gets flushed by the dealer, every 100K miles. I am careful to only use the long life coolant that this car calls for.
     
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  2. andrewclaus

    andrewclaus Active Member

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    First, you may need a Toyota-specific scan tool to read the codes you want to see. Many use the Mini VCI. My cheap standard reader will read P1116, though.

    Second, I'd look on the used parts market for a replacement tank. Here's one for $200, for example. Bleeding the system after working on it is critical and special tools and skills are needed, so you need someone familiar with the Prius to do the work. There may be a qualified independent mechanic in your area. But the Mini VCI is one of the tools, and with that you're part way to DIY.

    Third, where are you looking when you never see coolant? In the translucent white reservoir? You should be able to see the pink coolant by looking on the side of the reservoir. There are index marks there too. Yours probably needs to be cleaned well, and you may need extra light. If you're looking in the radiator neck, which requires removal of a shield, you should definitely see coolant to the top of the neck.

    Last, that's pretty amazing mileage you've gotten from the car. Congratulations.
     
  3. goldarrow

    goldarrow Junior Member

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    my 2009 prius had p1116 code along with p1121, changed coolant water valve and fixed both codes. coolant control valve is about $70 and 2 gallons of coolant $20/each, but used about 1.5 gallons.
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I do not understand this statement. How often do you check the radiator and add fluid? You should check this sufficiently often so that most of the time, you see the radiator fluid level at the top of the radiator.

    If you "never see fluid" then you obviously have air in the system. That might be caused by a leak (for example, at the engine coolant pump bearing) or may be caused because the system was never completely purged of air when the coolant was drained and refilled.

    The presence of air in the system could cause DTC P1116 to appear. The failure of the pump located in the left front fender also could cause this. If you hear the pump running for a few seconds upon startup and shutdown, then the pump probably is OK. "Noisy" is OK, that is much better than not hearing the pump at all.

    The coolant level should always be at the very top of the radiator neck and the overflow container should have fluid up to the full mark.
     
  5. rposton

    rposton Member

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    Patrick, yes. I would think so, but not in this Prius, even after dealer coolant change. I can add fluid till the top of the core is covered, but it seems to go back to being somewhere just below the core in a week or so. I have just assumed the dealer knows more about this than I do.
     
  6. michaelk87

    michaelk87 Junior Member

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    If I may jump in (2005 Prius Gen II 220,000 miles):

    Am throwing a P1116 and P1121. From what I see here, it suggests that fixing P1121 by replacing the pump would cost ~$100 + sweat equity if I self-repair, and might take care of the P1116. So I'd be curious to know if this is truly possible.

    This is the second time. The first time (appx. 180,000, if I recall), though the car was out of warranty, the 1-800 Toyota customer service lady authorized my local dealer to repair it for free. I had found an expired service bulletin on the internet, and she agreed to honor it even though it was expired.

    But there's a couple of flies in the ointment. My mechanic states that though the flow valve has nothing mechanically to do with the Air Conditioner, Toyota, in their engineering glory, has it tied logically somehow to the compressor so that if the valve don't work, neither will the Air Conditioning compressor. My Air Conditioner has not worked for some time. (Long before the OBD code showed up.)

    So first of all I ask if anyone knows if this is true?

    My air conditioning had failed some time before the flow valve OBD code showed up. Didn't have A/C in my cars when I was a kid. Figured I could live without it now. It did not come on after the first repair of the valve.

    However, all things Prius being inter-related like Rube Goldberg on steroids, it turns out that the HV battery deponds on a cool cabin temperature, little did I know. There's no point in pursuing this valve repair until I've reconditioned my HV battery. (Fodder for a different thread). But could it be that my ultimate salvation rests precariously on a $70 valve and $30 worth of coolant?

    I need a silver lining while I currently work through the HV battery issue. (Is looking like under $400 for a DIY reconditioning.)
     
  7. JC91006

    JC91006 Senior Member

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    Check and see if there's enough coolant in your radiator, that might be the problem if you are low or have air in the system
     
  8. dolj

    dolj Senior Member

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    It does no such thing.

    P1121 2006 TOYOTA PRIUS - Coolant Flow Control Valve Position Sensor Circuit Stuck

    Possible causes
    - Coolant Flow Control Valve (Stuck or Clogged Cooling System)
    - Faulty Coolant Flow Control Valve Position Sensor
    - Coolant Flow Control Valve Position Sensor harness is open or shorted
    - Coolant Flow Control Valve Position Sensor circuit poor electrical connection
    - ECM

    The first option is the most likely.


    P1116 2006 TOYOTA PRIUS - Coolant Temperature Sensor Circuit Stack for Coolant Heat Storage System

    Possible causes
    - Coolant Heat Storage Tank
    - Faulty Engine Coolant Temperature (ECT) sensor for CHS (Coolant Heat Storage)
    - Low engine coolant level
    - Engine Coolant Temperature (ECT) sensor for HST harness is open or shorted
    - Engine Coolant Temperature (ECT) sensor for HST electrical circuit poor connection
    - Faulty engine coolant thermostat
     
  9. ben sier

    ben sier New Member

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    my is the same as yours, has p1116 code , i change the sensor on the thermos tank, but came back, but today i change the coolant control valve, and that solve the my code p1116 code, just buy it on ebay and installed it, it cost only 56$. hope these help everybody here, because i look for the answer on my problem but cant find any answer that its only the coolant control valve,
     
  10. jdbertron

    jdbertron Junior Member

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    I had P1116 and P1121. I changed the coolant pump this week end. Trying to save the coolant is impossible so when I was done I refilled about 1 gallon into the plastic coolant container behind the radiator.
    I also put some in the radiator by disconnecting the little hose for the engine block. It looks like that helps vent the air.
    I also opened the bleed valve to the right of the radiator while running the engine in inspection mode. It quickly started shooting coolant everywhere. I closed everything up and ran the car around the block for a couple of miles.
    This morning in 21F temperature as I drove to work, I got the red triangle and a temperature warning. I stopped.
    From what can tell, the plastic compartment is still full, so is the inverter coolant container. There are no leaks.
    I hear the pump do its thing to swap coolant in the thermos storage when I stop the car. I noticed the cabin stayed cold as I drove for about 20 minutes. Now I'm at a coffee shop on the way to work waiting for the car to cool. I'll check the radiator level when it's cooler.
    Can anyone give me a clue about what I should do now ?
     
  11. jdbertron

    jdbertron Junior Member

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    Never mind. I think this answered my questions.
     
  12. JC91006

    JC91006 Senior Member

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    Your radiator needs to be filled and the 3 way valve needs to be changed. There is a plastic cover that covers the radiator cap, that's where you have to fill the coolant for the engine.

    P1121 is not the fault code for an inverter pump. So I'm a little confused where you filled the new coolant, the inverter pump cools the electric motor (different coolant loop from the radiator)
     
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  13. jerrymildred

    jerrymildred Senior Member

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    This is incredibly confusing.

    P1116 is for the temperature sensor at the coolant recovery tank for the inverter coolant. @JC91006 already covered the P1121. Why did you change the inverter pump? AND THEN try to fill and bleed the engine coolant? Now that you have changed the inverter pump, you need to fill and bleed that system. This one here:
    Screen Shot 2020-01-13 at 3.22.27 PM.png
     
  14. jdbertron

    jdbertron Junior Member

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    Well, folks, almost a year later, and it happened again. This time I took it to a mechanic. They changed the 3 way coolant valve and yet, I still get a code P1121 again. I'm not getting heat in the cabin, and my OBD2 reads ECT temperatures of 200 when in 'maintenance mode'. Did they just forget to burp the coolant ? Could it be the thermostat ?
    It also threw a P1150 , something to do with the Coolant Storage. So weird.
     
    #14 jdbertron, Nov 4, 2021
    Last edited: Nov 4, 2021
  15. JC91006

    JC91006 Senior Member

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    probably didn't bleed the system. Open the radiator cap (when the car is cold) and fill it with coolant. Then turn on the heater and let it circulate, add coolant when the level goes down. Heater should work after air is bled out and radiator is full
     
  16. ChapmanF

    ChapmanF Senior Member

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    I think I missed this thread earlier, but just now noticed #13 has a mistake that makes things even more confusing....

    P1116 has to do with the heat storage system for the engine (not the inverter) cooling system.

    Now that that's out of the way ...

    if air-burping the system as above doesn't bring the cabin heat back, a not-yet-completely-solved issue with the coolant control valve is another very possible explanation for a lack of cabin heat.
     
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  17. jdbertron

    jdbertron Junior Member

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    Thanks, I'll try that in the morning. Love you guys.
     
  18. jerrymildred

    jerrymildred Senior Member

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    You are right. You know how you mean to say one word and another comes out of your mouth? Sometimes that happens with fingers, too. Can't believe I did that! :oops: Thanks for catching and correcting it. Especially since it's too late now for me to fix it.
     
  19. ChapmanF

    ChapmanF Senior Member

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    Happens to me all the time. Also that thing where I will type wone word using some of the letters that belong in the next one I'm thinking about.
     
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  20. jerrymildred

    jerrymildred Senior Member

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    And sometimes, when talking to someone and mentioning someone else, I'll instead use the name of the person I'm talking to. The brain is a strange thing.
     
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