Weird P1121 after valve replaced

Discussion in 'Gen 2 Prius Technical Discussion' started by Ruming, Nov 27, 2020.

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  1. Ruming

    Ruming Junior Member

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    Bought a 2004 Gen2 210,000 km two weeks ago. The seller said there used to be ECL as the known issue, but everything was ok after he had the coolant valve replaced 2 days before. Driven for about 600km since then.

    The light comes on today, OBD II says P1121. Cleared, comes on again.

    Checked the coolant, both inverter and engine reservoir seem to have above the min level coolant. Car blows warm air with no problem.

    Need inputs on the possible root cause or likelihood on these below from my research so far:

    1. Mechanic didn't do it right. a)problematic (used) part installed, b)coolant wasn't drained/refilled correctly, air in cooling system, could this cause ECL after driving 600km?

    2. Loose/rotten electric connector

    3. Coolant leakage (I didn't find any but will check again)

    4. Bad ECM

    5. Seller lied
     
    #1 Ruming, Nov 27, 2020
    Last edited: Nov 27, 2020
  2. Ruming

    Ruming Junior Member

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    Checked coolant, full under radiation cap and in both reservoirs.

    Cleared the code, tested 2 miles, nothing happened.
     
    #2 Ruming, Nov 28, 2020
    Last edited: Nov 28, 2020
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    All your suggestions could be possible (except for coolant leakage- it would cause overheating instead of that code.). You need to do some checkout next. Open the hood and look down between the transmission and radiator (below the inverter) . The coolant valve is there, with two hoses heading back towards the trans and the third pointing straight down. The valve and its bracket that goes the the driver's side frame should be bright and shiny if it's new.

    If it's not shiny then it ain't new and you should replace it and recheck. Another thing to look at is underneath the left front corner of the car is the heat storage tank (thermos bottle). At the bottom of the tank is a temperature sensor - I believe the ecm uses that to help figure out if the valve has actually moved. You want to see if that sensor or its wiring are damaged.

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Nov 28, 2020
  4. Ruming

    Ruming Junior Member

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    Thanks for helping.

    The bracket look okay, valve has some white removable spots on it (I put both before and after pics), not sure if it's brand new. I'll call the shop next week to find out.

    Good news is a rag on the bottom cover under the valve. At least someone has done something about the cooling system.

    Didn't find a way to access the CHS sensor. Will check the manual later.

    Still trying to understand when the value should move. That is probably when I should expect the next check engine light. IMG_20201128_124308.jpeg IMG_20201128_124118.jpeg IMG_20201128_124145__01.jpeg IMG_20201128_124400.jpeg IMG_20201128_124449.jpeg

    Posted via the PriusChat mobile app.
     
    #4 Ruming, Nov 28, 2020
  5. Ruming

    Ruming Junior Member

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    Tried resetting the light a couple of times. It's quite obvious the light comes on every time I start the car, no matter overnight or after a long trip.
     
    #5 Ruming, Nov 29, 2020
  6. Ruming

    Ruming Junior Member

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    Called the shop the seller had the valve replaced. The owner said they only use new parts. From the picture above I believe it's true. Then it's quite unlikely for a new valve to fail in 2 weeks/1000km.

    Will check CHS sensor and wiring, but one question: Shouldn't I have got P1116 and P1150 if the sensor/wiring failed?
     
    #6 Ruming, Nov 30, 2020
  7. Ruming

    Ruming Junior Member

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    upload_2020-11-30_19-46-5.png

    Where the clogging might happen, inside the hoses/radiator or among the fins of the radiator?
     
    #7 Ruming, Nov 30, 2020
  8. John Tyler

    John Tyler New Member

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    I had the same code....I changed out the coolant control valve ($52.00) myself. Still had the code. I learned on YouTube to run the water pump with the radiator cap off (do it cold and while warming up). there is a certain jumper place to do it (find it on youtube), and it runs the water pump. You do that for only about 5 seconds at a time, and you will see the radiator level drop (significantly). Keep using the jumper where prescribed (easy)....and run the pump to clear all of the air out of the system. After filling the radiator again with antifreeze about five times, it was finally actually full. The check engine light went out immediately! JT
     
    #8 John Tyler, Dec 1, 2020
  9. Ruming

    Ruming Junior Member

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    Thank you John. I'll definitely give a try.

    When did you have the code, right after the change or a while later? Mine start throwing the code after about 600km. Checked coolant is full. If the engine runs with air in the system, should I be more concerned of overheating/damage than the code itself?
     
    #9 Ruming, Dec 2, 2020
  10. Ruming

    Ruming Junior Member

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    Ran the pump from CHS relay with multimeter and half funnel of coolant on radiator. 20 sec 3 times. The current reads 3.07A, but not a single bubble shows up in the funnel.

    Does it mean a lot of air in the cooling system? Why didn't it bleed?
     
    #10 Ruming, Dec 4, 2020
  11. Ruming

    Ruming Junior Member

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    [Status]

    Radiator and reservoir full of coolant. Road test with max heat and low fan speed, very hot air blown. Reservoir coolant level does not drop after 5miles test drive. Engine temp normal 176F max with ambient 37F. ECL P1121 cleared but comes back almost every time car is started. Water sloshing sound after switch off. Bought clear vinyl tube for bleeding air from radiator. Ordered Mini VCI.

    [Likely Causes]
    1. Replaced valve goes wrong again (it could be aftermarket part)
    2. Valve stuck by debris in coolant (the previous owner may not have changed coolant)
    3. CHS sensor wiring
    [Action Plan]
    • Call the shop again to confirm aftermarket or OEM part
    • Check sensor wiring
    • Try bleeding air from CHS relay socket with radiator bleed valve open.
    • Plan to change coolant in near future
     
    #11 Ruming, Dec 5, 2020
  12. Ruming

    Ruming Junior Member

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    Tried CHS relay again with radiator cap off and radiator bleed valve open (6mm hex), 20 sec x 3 times, nothing happens at all.

    Coolant pump draws about 3.2A current which is lower than 4A normal value suggested in most Youtube channels. Does it suggest air in the coolant passages?
     
    #12 Ruming, Dec 5, 2020
  13. Ruming

    Ruming Junior Member

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    After cleared a couple P1121 in the last few days, it throws P1122 today. Does it suggest high likelihood of valve failure? upload_2020-12-8_20-42-58.png
     
    #13 Ruming, Dec 8, 2020
  14. mr_guy_mann

    mr_guy_mann Senior Member

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    Fairly high that the valve is bad, moreso if it is not OE replacement part. It is also possible that there is a problem with the connector or wiring. If the valve was OE then you might want to find out what warranty Toyota has - if any.

    Ideally you would monitor the valve feedback signal with a scope (or at least a good multimeter with a bar graph in addition to the numeric display) while using techstream to command the valve throygh all three positions. If the signal acts up in the same area every time then you know it's the valve.

    Since few people have that capability then you have to guess, and replace the valve (with a good part) and see.

    Posted via the PriusChat mobile app.
     
    #14 mr_guy_mann, Dec 9, 2020
  15. tidesofthesky

    tidesofthesky Member

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    The real Toyota valve has Denso stamped on it, so you could take a look with a mirror for that to see if it's oem. I've got this same code- changed the valve out with one from wrecking yard, still have code, and also started getting p1116. . I need to look at the CHS tank, too. I have no problem ordering a new valve, but would love to verify first since it seems that a lot of people change the valve and still have the code return.

    Posted via the PriusChat mobile app.
     
    #15 tidesofthesky, Dec 12, 2020
  16. Ruming

    Ruming Junior Member

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    Called the shop again. The owner said he "don't remember" where he got the valve.

    Anyway, I'll just try a new OEM valve and change the coolant as safety measure to a used car.
     
    #16 Ruming, Dec 15, 2020
  17. Ruming

    Ruming Junior Member

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    Update: problem solved by changing the control valve to genuine part. IMG_20210207_122841.jpeg

    Posted via the PriusChat mobile app.
     
    #17 Ruming, Feb 7, 2021
  18. ChapmanF

    ChapmanF Senior Member

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    When an original-equipment valve starts acting up, if diagnosis reveals it's the position sensor in the valve and not a mechanical issue with the valve itself (can be either), there may be some value in just refurbishing the original as opposed to putting in a questionable aftermarket replacement.
     
    #18 ChapmanF, Feb 7, 2021
  19. mr_guy_mann

    mr_guy_mann Senior Member

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    #19 mr_guy_mann, Feb 7, 2021
  20. caravan2429

    caravan2429 Junior Member

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    I guess it is circuit communication issue for Dorman aftermarket valve. It works fine but just randomly pops up the code and CEL.
    However in your case, it is more abnormal because that is too often to get the code, likely some faulty circuits inside.
     
    #20 caravan2429, Feb 8, 2021
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