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P1116 code and no heat!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Eric Cadora, Oct 20, 2018.

  1. Eric Cadora

    Eric Cadora New Member

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    The P1116 code has been coming on for a couple months intermittently but nothing seems amiss until earlier this week when I got cold enough to use my heater. It just blows cold on Max Hot. Yesterday I bled the coolant system since that came up several times in this forum and in my Google searching, but I haven't found anything about P1116 and no heat as an issue that's connected.
    Any beta would be greatly appreciated.
     
    #1 Eric Cadora, Oct 20, 2018
  2. exstudent

    exstudent Senior Member

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    Great. You've been ignoring the CEL for how many monhts?!

    Something caused that code to trigger.
    1) Did you even open the radiator cap to check if there was coolant inside the radiator?
    2) What color is the coolant if you see any?
    3) Do you see any dried coolant near the engine water pump, or evidence of coolant being sprayed inside the engine compartment?
    4) Did you test the sensor at the CHST (Coolant Heat Storage Tank), aka "thermos"?
    5) What is the maintenance, or lack of maintenance history for this car, esp the engine and inverter cooling loop drain/fill?
    6) Describe in relevant detail, how you "bled" the engine coolant loop.
    ​
    Contact member "3prongpaul" Maybe he might know of a competent Prius shop in SLC, UT.
     
    #2 exstudent, Oct 21, 2018
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    What was your method to bleed the coolant system? Did you bleed the air out of the coolant heat recovery system, by forcing the pump for that system to run? DTC P1116 is logged by the engine ECU when the coolant heat recovery pump runs, and the temperature sensor at the outlet of the canister for that system does not show the appropriate temperature of the fluid coming out of the canister.

    If you did not do this, or if you were not aware that the coolant heat recovery system exists, please see my posts #22 and #42 here, as well as the surrounding commentary:
    Changing engine coolant | Page 2 | PriusChat
     
    #3 Patrick Wong, Oct 21, 2018
  4. Eric Cadora

    Eric Cadora New Member

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    Hi Patrick. Thanks for the wholly undickish response. That other dude clearly needs a hug, or some damn thing.

    I did force the pump to run when I bleed it. There was no air whatsoever in the system. I had the water pump replaced 5 years ago at the local dealership so the coolant was changed then. I have never replaced the inverter fluid, which I will do soon.

    Here's some things worth noting: I have been getting the accelerator pedal clearance code for a couple years now. I bought a used one on Ebay last year but the code still comes on. No biggie, I clear the code long enough to pass inspection and have just been tolerating the check engine light, checking the codes every now now to make sure another code hasn't presented itself. A couple of months ago is when I first saw the P1116 code. No red or yellow triangle, just the check engine light. I cleared it and it was gone for a month or so until I checked it recently and it was back on again. Engine has never overheated and have never had any leakage of coolant. I cleared it a few days ago and it has yet to return. I guess at this point I should check the the sensor on the thermos, huh? Is it possible that this code and the lack of heat are 2 separate issues?

    My repair skills are limited but I've owned the car since new and try to do all the basic maintenance myself before taking the vehicle to a mechanic. Thankfully, she has been by and large super reliable.

    Thanks again for the non condescending response.

    Eric
     
    #4 Eric Cadora, Oct 26, 2018
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Eric,

    OK - it looks like you are located in Salt Lake City, UT and if so, the ambient air low temps are approaching freezing.

    It is possible that DTC P1116 and the lack of cabin heat may be two separate issues.

    One way to check the thermos sensor, would be to use an instant read IR thermometer on the canister outlet to measure the temp of the outlet while the car is IG-OFF and has been resting overnight. Then make the Prius READY, wait for the engine to start so that fluid is circulating, and see whether the outlet temp increases as hot fluid from the canister passes through the canister outlet. If the fluid temp increases, but DTC P1116 is logged, that would imply the sensor has failed. If the fluid temp does not increase, then the sensor is not the problem.

    Regarding the lack of cabin heat, if you do not hear any air bubbling in the cabin heater core (which would be a sign that air remains in the coolant system despite your recent bleeding efforts), and the cabin heater still does not work after you've driven the car on the freeway for an extended period, it could be that the engine coolant valve is stuck so that coolant is not flowing to the cabin heater core. Often DTC P1121 would be logged in that eventuality.

    Also, there is an electric coolant pump which is supposed to circulate engine coolant to the cabin heater core when the engine is not running, and maybe that pump has failed.

    Finally, the Prius engine doesn't produce that much heat in the winter, and the heat is supplemented by a couple of PTC (positive temperature coefficient) electric heating elements. Maybe there is a problem with those heating elements. There are three related fuses: 50A PS HTR, 30A PTC HTR1, and 20A PTC HTR2.

    Some owners will block the lower grille vent with a pool noodle or similar item, to restrict air flow to the radiator, thus allowing the engine to heat up more in the winter.
     
    #5 Patrick Wong, Oct 26, 2018
    Last edited: Oct 26, 2018
  6. Eric Cadora

    Eric Cadora New Member

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    Thanks for the beta, Patrick. I'm going to take it to a local retired Prius mechanic on Monday to check her out but now that you mention it, I'm not so sure I've recently been hearing the electric coolant pump kick in after I turn the car off. I'm going to really pay attention to that this weekend. Thanks again and I'll keep you posted.
     
    #6 Eric Cadora, Oct 27, 2018
  7. exstudent

    exstudent Senior Member

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    Its called sarcasm. Sarcasm | Definition of Sarcasm by Merriam-Webster


     
    #7 exstudent, Oct 28, 2018
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