Help! Torque converter went bad?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Lemonhead228, Aug 12, 2025.

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  1. Lemonhead228

    Lemonhead228 New Member

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    I did drove the car around for another week when it happened to trigger a code but nothing.

    Im going to try and clean all the terminals and connections. Hopefully it helps.
     
    #21 Lemonhead228, Aug 29, 2025
  2. hurricos

    hurricos Junior Member

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    I am struggling to believe you aren't getting any codes or blink codes. How are you trying to retrieve error codes from the system?
     
    #22 hurricos, Aug 30, 2025
  3. Lemonhead228

    Lemonhead228 New Member

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    Obd2 scanner. I even left it plugged in for live data to se if it catches anything. Nothing.

    I just cleaned my bus bars and sanded down all the connections. It wasn't super corroded but did have little build up. I believe all my battery are in good condition but what Tombukt2 said does makes sense. Battery read good volts but might not be getting full amps because of connections. Will up date this week when I get the battery back into the car.
     
    #23 Lemonhead228, Sep 2, 2025
  4. ChapmanF

    ChapmanF Senior Member

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    Are there any warning lights illuminated on the dash?

    If there aren't, it's unsurprising to see no codes. Nearly all trouble codes, when set, will light at least one warning light.

    If there are no lights and no codes, it's possible that you're worrying (as suggested upthread) over behavior that is within the range of normal for your car's age and condition, and doesn't cross any threshold that would set a code.

    If there are warning lights and the code reader you're using says no codes, that's most likely the fault of the code reader you're using, and the thing to do would be to select another one after reviewing this thread:

    Gen2 OBD2 app review | PriusChat
     
    #24 ChapmanF, Sep 2, 2025
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  5. Lemonhead228

    Lemonhead228 New Member

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    My catalytic converter was clogged!! Got a replacement on and it rides like new!! Back to 45mpg baby!

    I put the battery back on and still have the issue. Did a full tune up, spark plugs, air filter, etc.. same thing.

    I read up some more on and some mention the cat could be clogged which made sense because it won't throw a code for it.

    Hope this helps anybody that has the same problem.
     
    #25 Lemonhead228, Sep 10, 2025 at 3:42 PM
    Mendel Leisk, bisco, hurricos and 1 other person like this.
  6. bisco

    bisco cookie crumbler

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    congrats!
     
    #26 bisco, Sep 10, 2025 at 9:17 PM
  7. hurricos

    hurricos Junior Member

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    Thank you for persisting. I'm glad to know now that real loss-of-power can occur without fault codes.
     
    #27 hurricos, Sep 11, 2025 at 9:41 AM
  8. gdanner

    gdanner Member

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    Do you have any idea what caused the CAT to get plugged up?

    Many years ago I had a car (not a Prius) where the CAT got totally plugged up.

    The cause turned out be a very small crack in the aluminum head of the engine. It intermittently let enough coolant into one cylinder to build up a thick layer of residue inside the CAT. Curiously the engine ran OK up until the CAT became totally plugged. I had noticed the car was slowly losing coolant, suspecting a leaky water pump seal.

    I kept the coolant topped up while waiting for enough spare time to replace the water pump. The car was needing only a cup or two of coolant added per week...

    ...but then, all of a sudden, the engine had almost no power at all. I could scarcely get the car up to 25 MPH. When I looked under the hood the exhaust manifold was glowing red hot.
     
    #28 gdanner, Sep 12, 2025 at 2:15 PM
    Last edited: Sep 12, 2025 at 2:23 PM
  9. Lemonhead228

    Lemonhead228 New Member

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    Thank you everybody for helping and inputs. I was really stuck and had no clue.

    Yes I was running out of ideas of what it could be and was stuck after I tried troubleshooting the hybird battery.
    I'm thinking the cat material had melted and just clogged the honey cones holes so the engine couldn't breath. After research, I cracked the header and force an exhaust leak to see if it was a clogged cat and it drove a ton better. Motor breath a lot better and no lag and struggle anymore. Order replace on ebay for $70 lol
     
    #29 Lemonhead228, Sep 12, 2025 at 7:55 PM
  10. ChapmanF

    ChapmanF Senior Member

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    A prolonged episode of engine misfiring (for whatever reason) is something that can melt the catalyst honeycomb like that. The fuel that isn't getting burned in the cylinders just travels down the exhaust and burns in the converter, heating it up to the melting point.

    Any time the engine control module detects misfiring severe enough to do that, it flashes the check-engine light.
     
    #30 ChapmanF, Sep 13, 2025 at 10:22 AM
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