Seafoam full can in the tank, now runs bad. Can this be fixed. how?

Discussion in 'Gen 2 Prius Main Forum' started by monoshock, Mar 24, 2026 at 8:14 PM.

  1. monoshock

    monoshock Member

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    Well I've used seafoam for many years with no problems. However I forgot and dumped a whole can in my 2004. Now it runs weird. 210k miles. How can I fix my mistake?
     
  2. dolj

    dolj Senior Member

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    Define weird.
     
  3. ChapmanF

    ChapmanF Senior Member

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  4. PriusCamper

    PriusCamper Senior Member

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    How many gallons was it mixed in with/how full was tank? How many gallons have you added and how many miles since whatever "weird" means started?

    Also when was last time you replaced plugs and cleaned throttle body and MAF sensor?
     
  5. monoshock

    monoshock Member

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    The tank was full. Around 200 miles is when the problems started, before the car ran great. i connected two different scanners and both show catalytic problems but with no codes. Hope the catalytic isn't clogged from carbon being broken loose from the seafoam. I'll post a picture of the scanner.
     
  6. pasadena_commut

    pasadena_commut Senior Member

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    How does a scanner show a catalytic problem but no code???
     
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  7. PriusCamper

    PriusCamper Senior Member

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    If you've already driven 200 miles you have plenty of room to add more fuel and dilute the sea foam... And yes the catalytic problems are indicating that you got bad gas that's not combusting normally. Hopefully you put the seafoam in first so it mixed well? Also, maybe you bought a bad tank of gas at same time you put Seafoam in?
     
  8. Brian1954

    Brian1954 Senior Member

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    Waiting for the picture.
     
  9. monoshock

    monoshock Member

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    20260325_090953.jpg 20260325_090719.jpg

    Here is what the scanner shows but no codes. I ran the car in place for 10 minutes and it runs fine. One thing that it starting doing before I parked it is the ICE would run when setting still and the hybrid battery is full. The car never did that before. I have a Nexcell hybrid battery in it.
     
  10. dolj

    dolj Senior Member

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    My condolences if it is one of their lithium packs. Do some research on this site so you know what is in your future.
    Code:
    site:https://priuschat.com/ Nexcell Lithium
     
    #10 dolj, Mar 25, 2026 at 8:36 PM
    Last edited: Mar 25, 2026 at 8:42 PM
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  11. monoshock

    monoshock Member

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    It been fine for over 5 years now.
     
  12. Brian1954

    Brian1954 Senior Member

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    What brand and model number of scanner are you using?

    Most scanners are not capable of reading all the trouble codes that a Prius can have. Read post #1 and post #37 in this thread, https://priuschat.com/index.php?posts/3246758
     
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  13. dolj

    dolj Senior Member

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    Well you have done better than most. It is most like very quickly coming up to EoL.

    You still haven't stated in what way your car was behaving 'weird', unless you mean this:
    That is quite normal if the battery ECU detects that the voltage is above its 80% threshold. It will run the engine to lower the voltage down to where it is happier with it.
     
  14. Brian1954

    Brian1954 Senior Member

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    You must have an early version of NexPower's lithium hybrid battery.

    Can you use the Dr Prius app to check the hybrid battery data and to check for hybrid battery trouble codes?

    On the dashboard, are any warning lights tuned on?

    EDIT: Based on this thread that you created, https://priuschat.com/index.php?posts/3265366, you ordered the lithium hybrid battery in July of 2022. That makes you battery less than 4 years old.
     
    #14 Brian1954, Mar 25, 2026 at 8:49 PM
    Last edited: Mar 25, 2026 at 9:06 PM
  15. ChapmanF

    ChapmanF Senior Member

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    That's a picture of the readiness display for the various monitors (self-tests). Looks like the only ones showing ready are the continuous ones like misfire and fuel. The ones that depend on tests the car occasionally runs are showing not ready.

    One time you'll always see that is when someone has recently done a code clear. In addition to clearing codes, that also resets all the noncontinuous monitors to not-ready, and they only come back to ready one by one as you drive around for a while and the different self-tests get run.

    (That's one reason not to have too itchy a trigger finger on the code-clear button if there is an inspection coming up soon, because the inspector will send you home if you show up with the self-test monitors not ready.)
     
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  16. pasadena_commut

    pasadena_commut Senior Member

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    The cat can take a while to come up to temperature to be "Ready" if the ICE isn't running continuously. Drive it on the highway for 10 minutes and check again. The O2S (O2 Sensor) might also take a while. Ditto for Evap.
     
  17. ChapmanF

    ChapmanF Senior Member

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    The various self-tests have their own various schedules for when they run.

    EVAP is an extra-special one, because it's not even one that runs while you're driving. It runs five hours after you park and shut the car off (sometimes longer depending on temperatures).

    There are also dependencies between the tests. For example, the catalytic converter self-test cannot be run until after the air-fuel ratio sensor test and the heated oxygen sensor test have run.

    Generally they'll all manage to get back to completed status eventually if you just keep making normal use of the car over a week or so.

    If time is pressing, you can start looking up the "confirmation driving patterns" in the repair manual for the ones that haven't completed yet.
     
    #17 ChapmanF, Mar 25, 2026 at 9:02 PM
    Last edited: Mar 25, 2026 at 9:07 PM
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