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Check Engine Light -- 2001 Prius

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by gippah, Oct 1, 2007.

  1. gippah

    gippah New Member

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    I have a 2001 Prius and the 'check engine' light came on yesterday, about a day after filling the tank up. The tank was still on full. I'm NOT referring to the warning triangle that can come up on the main screen, but the engine light in the cluster.

    On most cars, the 'check engine' light usually means an emissions or transmission problem. Most notably the light is triggered when filling the car with bad gasoline or leaving the gas cap off / having it on too loosely.

    As with other cars, the definition of what this light means on the Prius is obscure in the manual. Is this light treated the same as other cars -- being an emissions problem -- or could there actually be something wrong with it?

    The car is performing just as it has been, though as I said I did just fill it up with gas.

    Toyota likes to charge $90 to run any diagnostic so I'd prefer to have a feel for what the problem is before I take it in and ask them.
     
  2. gippah

    gippah New Member

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    I brought it in to a Toyota dealership and they are saying that the catalytic converter has gone, with a replacement costing $2100.

    This seems kind of weird to me that it would go so quickly, one would expect a part like this to have a more gradual failure, barring physical damage or abuse.

    The last few times I have taken either of my Toyotas to Toyota dealerships I haven't been very impressed, it seems to me that they just hook it up to their computer and don't do any real troubleshooting beyond that. Since I've seen this at multiple dealerships now I'm thinking this is what Toyota is telling them to do.

    Anyway, I'm digressing. Assuming the more likely scenario of me just having a bad tank of gas, how long will it take for the 'check engine' light to clear?
     
  3. gippah

    gippah New Member

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    I got a code from the dealership, I'm hoping this is the right diagnostic code and it will help someone here isolate this better:

    P0420
     
  4. gippah

    gippah New Member

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    So none of the techies here have any insight on this? Will a universal catalytic converter work on the Prius? What else could it be with this error code, as I think it's a safe assumption that the dealership didn't check a single thing?
     
  5. efusco

    efusco Moderator Emeritus
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    We've only got a handful of 1st Generation owners here so good info on tech issues might be harder to come by. Have you checked the Yahoo! 1st Gen. Prius site or the Prius tech site at Yahoo!?
     
  6. gippah

    gippah New Member

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    Well if no one knows, and the check engine light doesn't disappear after a new tankful of gas or two, I'll just get a universal catalytic converter for it.

    $100 vs. $2200 is a pretty huge difference.

    Thanks for the direction. :)
     
  7. efusco

    efusco Moderator Emeritus
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    I'd check the sites I recommended before wasting $100 on a universal Cat. I suspect that the emissions controls require some pretty specific things and that the Cat is part and parcel to that proper operation. While the universal may work, I suspect it won't eliminate your CELs and may even inhibit proper operation of the car.

    I don't know this for fact, but knowing the Prius I'm suspicious of that and it's definately worth asking around where the majority of folks most familiar with the Gen 1 hang out.
     
  8. galaxee

    galaxee mostly benevolent

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    cripes. yes, we all know nothing. you seemed to have the issue figured out but ok :rolleyes:

    this is what i can dig up on TIS, but the expert is busy at home and i'm at work.

    DTC P0420 Catalyst System Efficiency Below Threshold

    Catalyst Deterioration Monitor Description
    MONITOR SUMMARY
    The ECM compares the output waveforms from the oxygen sensors installed on the front and rear of the
    catalyst to determine if the performance of the catalyst has decreased beyond specified limits. The waveforms
    from each sensor continue changing from rich to lean, lean to rich. When the catalyst functions normally,
    the output waveform cycle of the rear oxygen sensor is much longer than that of the front oxygen sensor.
    When the output waveforms from the front and rear oxygen sensors change in the similar cycle, the ECM
    determines that the performance of the catalyst has decreased below specified limits. The ECM will illuminate
    the MIL and a DTC is set.

    so it may be gradual but you hit the threshold when the CEL kicked.
     
  9. gippah

    gippah New Member

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    Yes, you're not saying anything unknown by posting that.

    However, the P0420 code isn't triggered by the CC itself, but it is instead triggered by trying to match whether or not the sensors in front of it and behind it are giving expected readings. So, of course, the problem could be the sensors. I'm hesitant to believe that the mechanic troubleshot anything. For a $2200 repair, of course I have to be shown by the mechanic who worked on the car exactly what he looked at. Toyota dealerships aren't set up to do this, however, customers are never face to face with any of the mechanics.

    The real question is, how will a universal CC affect the Prius? I can tell you that there is a 0% chance that I am going to spend $2200+ tax on a catalytic converter when I can get one for $50 and a new set of universal sensors for another $50.
     
  10. efusco

    efusco Moderator Emeritus
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    You might be able to pick up a salvage Cat off a 1st gen complete with sensors for pretty cheap...I realize $2200 is dang high, but I can't imagine the salvage are that much, maybe more than the $100 universal, but to be sure that you've solved the issue it may well be worth a couple hundred extra.
     
  11. gippah

    gippah New Member

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    I thought about that, however since a new CC would go for $1700+ tax just for the part, one has to figure that a salvaged one would go for $600-$1000 (unless I have a friend who can hook me up, which I don't). That's still too much .... and of course who knows how long a salvaged part is going to last.
     
  12. phantomracer

    phantomracer New Member

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    I get a similar code on my chevy truck (obd1 though, but similar). Ended up being a bad o2 sensor.

    I think i would try to replace the 02 sensors before dropping in a new cat! how is the air filter and MAF?

    If it is the cat..find out WHAT caused it to fail,otherwise the new one will fail too most likely.
     
  13. galaxee

    galaxee mostly benevolent

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    if you read what i quoted, you basically repeated it in your reply.

    the repair manual indicates to check for exhaust leaks, harness opens or shorts, and to check output of both o2 sensors before diagnosing cat as problem.

    if you don't believe your mechanic went through the confirmation and secondary diagnostic steps, take it elsewhere before proceeding with that kind of expensive repair. if the cat isn't the problem, you're wasting your money even with a universal.

    DH never had an issue talking to his customers, especially prius owners. they would ask to talk to him when the writer was standing there looking clueless, again it's an individual thing. other techs may not be so inclined to spend time they could be using to make money to talk to a customer for free. the dealership where you are sounds pretty crappy.
     
  14. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    There is a cost of taking it to a dealer and getting a diagnosis. There is also a cost (and time) of just getting a new O2 sensor and putting it in yourself. I would just do the later because you will never be sure or happy unless you did it anyway. Just knowing that the big buck were required is worth the cost of an O2 sensor to me.
     
  15. gippah

    gippah New Member

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    From what I gather, this is what we're looking at that can trigger this code:

    - Leaks
    - Physical Damage
    - Bad Sensors
    - The CC actually being bad

    The Toyota dealership did their diagnosis but didn't explain to me what they checked, so I'm suspicious that they just looked at the error code. However, they want to replace two gaskets along with the CC, so if they did actually troubleshoot beyond the computer code it may be physically damaged or they found a leak. I will talk to them again tomorrow and hopefully get some better answers now that I will have better questions.

    For future reference, it does appear that a universal CC will probably work on the Prius. If I go that route I will post the results, though, to be sure.
     
  16. Frank Hudon

    Frank Hudon Senior Member

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    the cat on the Classic isn't a normal cat it's has and external HC absorber on it and a control valve in the front inlet of the cat that is controlled by a TVS that closes the valve when it's below the temp threshold and opens it above that temp. This forces the exhaust gas thru the absorber and into the cat thereby not overloading it when cold. When the valve opens the heat of the cat expels the HC from the absorber and forces it into the now up to temp cat where it's treated. These are no 200$ universal cats. If your in a state that has emmission testing they will in all likelyhood catch the output on the test or on the visual if your tester is up to date on the Classic Prius exhaust system.
     
  17. gippah

    gippah New Member

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    The HC absorber is a separate piece, from what I have been told. This is used to store vapors until the CC has warmed up and is only used for a couple of minutes after the car is started.

    Even if the HC is bypassed altogether by a universal CC, at worst the Prius will be acting like a normal car as far as emissions goes.
     
  18. Frank Hudon

    Frank Hudon Senior Member

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    <div class='quotetop'>QUOTE(gippah @ Oct 4 2007, 09:31 PM) [snapback]521572[/snapback]</div>
    climb under and have a look, the valve is integeral with the cat. The Classic cat is very small for even a sub compact and the computer is programed to provide a rich mixture to help warm it, a function of the retarded cam timing. Also the problem could be in the TVS or the actuator or the actual valve seized in the closed position.
     
  19. gippah

    gippah New Member

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    Hm. It's too bad I can't get you to look at it. I'm not having much confidence in what I've seen so far with this issue locally.
     
  20. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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