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Can I get away without Toyota parts for plugs, injectors, or coils?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusPaddler, Nov 11, 2024.

  1. PriusCamper

    PriusCamper Senior Member

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    Throttle body replacement is the only known repair method for Throttle body position sensor, because there's no way outside of the factory to calibrate if you just swapped the sensor.

    Sounds to me like there's no new problems with your car, just same problem you had before with unstable idle and you'll likely find P1121 again. Just put in another used throttle body from the wrecker. It's just some plug, nuts, bolts, clips, very easy job....
     
  2. dolj

    dolj Senior Member

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    ... and of course, the correct cookie cutter text for a P1121 is Coolant Flow Control Valve Position Sensor Circuit Stuck.

    There are plenty of posts in the Gen 2 forum about that, some of which will have the repair manual except for how to troubleshoot and repair this problem.

    This code will be set if any of the following conditions are detected:
    • Water valve position sensor output voltage:
      • No change despite the ECM sending a valve control signal or slow response
    • CHS tank outlet temperature sensor output:
      • 60°C (140°F) or more (when hot coolant recovery starts)
    • CHS tank outlet temperature sensor output:
      • No change despite the hot coolant being recovered
     
    #22 dolj, Nov 12, 2024
    Last edited: Nov 12, 2024
  3. ChapmanF

    ChapmanF Senior Member

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    Oh heck, was this another of the "somebody googled a P1 (manufacturer defined) code and got the meaning it has in some other model of car" stories?
     
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  4. PriusPaddler

    PriusPaddler Member

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    Yep. Been there done that 3x. The shop read the 1121 incorrectly because they didn't look it up for a prius.Specifically , so they replaced that position sensor needlessly.
     
  5. PriusPaddler

    PriusPaddler Member

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    Yes!! But that is old news except that they replaced the wrong part which means that part is relatively new for my car And not likely to be the issue today.
     
  6. PriusPaddler

    PriusPaddler Member

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    I have a lot going on at the moment with A family farmhouse and auction.

    Left my car at a Shop this morning telling them about the codes and the last time plugs were replaced.

    They just called and said plugs were bad and are now replaced car is done. But then added that I was a bit low on coolant!!!

    My son noticed that two or three weeks ago.. Doesn't that mean it has to be a head gasket?

    Aaaaargh. Even if it runs smoothly now, Why else would I be a little low on coolant so quickly?

    I'm tempted to call them back and ask if they even tested for a head gasket issue...
     
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  7. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Sounds like The Three Stooges Garage...
     
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  8. pasadena_commut

    pasadena_commut Senior Member

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    A bad radiator cap can result in unexplained coolant loss. The OP might very well have the original cap, and at more than 300K miles, it may be on its way out. There are no drips when this happens, the coolant is lost when hot, and evaporates leaving no signs. Pressure test the cap to see if it is still good. Note, I recently replaced a cap on an Accord with one from Gates (usually reliable parts) purchased from RockAuto (reliable vendor). I happened to have a pressure tester on loan, and in an abundance of caution, tested it before installing it. It was bad - wouldn't open at any pressure. So got a refund from RockAuto (for obvious reasons, they didn't want the part back) and bought an OEM Accord cap at a local dealer. Tested it too (paranoid by this point), it was fine, and problem solved. We had thought this might have been a bad head gasket, but with the coolant loaded with dye and the cooling system pressurized there were no leaks into any of the cylinders, nor were there any external leaks, nor any contamination of the oil or AT fluid. At that point pretty much all that was left was a bad cap.

    One thing about ordering multiple parts from RockAuto - they don't necessarily come from the same warehouse and the shipping times can vary dramatically. I have on occasion picked a different part (where it didn't make much difference, like for a cabin air filter) in order to get the parts faster. In cases of "needs to be Denso" then I just wait for the part.
     
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  9. PriusPaddler

    PriusPaddler Member

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    Thank you for that idea! They did say they saw no contamination of coolant on the spark plugs and no obvious leaks of coolant.

    The car has been running smoothly for 150 miles, but was not a cold start when I picked it up, so the real test will be tomorrow morning.

    Thank you all!
     
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  10. mr_guy_mann

    mr_guy_mann Senior Member

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    My usual test for a suspected head gasket leak is to get the engine hot. Then do a cooling system pressure test. Leave it pressurized overnight.

    The next day remove the spark plugs and look inside the cylinders with a videoscope. Even a few drops of coolant mean there's a leak.

    Posted via the PriusChat mobile app.
     
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