Ignition Coils, and Catalytic Converter, and Oil...Oh my!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by petersw, May 31, 2016.

  1. petersw

    petersw Junior Member

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    I've got a 2004 Prius with about 140,000 miles. Overall, the car has worked great, and I've kept up with regular service.

    Several months ago, I started having bad misfiring of the engine. When I got it into the shop, it turned out to be two faulty ignition coils. The shop advised me to replace them all, which I did. Soon afterwards, however, the CEL came on, indicating a P0420 - "Catalyst System Efficiency Below Threshold Bank 1".

    From reading online, this seems to be a common problem after having a bad ignition coil. I've tried the "home remedy" (Gummout), but the light keeps coming back on after I reset it.

    Now, I'm also starting to notice that the car is burning a lot of oil. So much so that after only 2500 miles or so, the Red Triangle warning comes on along with the oil can. When I checked, it was almost empty.

    So, my question is what to do next...Can the damaged catalytic converter impact oil use? Do I need to now spend $1k or so on a new converter, or should I be putting that money into another system on the car? I really don't want to give up the Prius, but I'm getting worried that it may be showing its age...

    Advice greatly appreciated!!
     
    #1 petersw, May 31, 2016
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Maybe the oil burning is the initial problem: it's clogging the CAT?
     
    #2 Mendel Leisk, May 31, 2016
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  3. petersw

    petersw Junior Member

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    Maybe, but I don't recall having any oil problem prior to the coils and CAT...
     
    #3 petersw, May 31, 2016
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  4. JC91006

    JC91006 Senior Member

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    The oil burning is probably what killed the cat. You haven't noticed oil burning because you've never checked. Only reason you noticed this time around, the warning light lit up with low oil pressure, which probably damaged the engine even more now.

    I'd suggest you save your money and buy another prius, this one can be scrapped for parts or for someone as a project.

    It'll need an engine, cat, hv battery in the near future, so unless you're prepared for all those repairs, I would just move on to another one
     
    #4 JC91006, May 31, 2016
  5. dolj

    dolj Senior Member

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    +1 to this. When the oil warning pops up it really means NO oil. Irreparable damage is done the the engine in this situation.

    When a car is using oil, drivers need to be checking the dip-stick every fill up and topping up as required.
     
    #5 dolj, May 31, 2016
  6. petersw

    petersw Junior Member

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    Ok, thanks for the troubling news... Next stop is to bring it into a garage that I trust and make the cost/benefit decision...
     
    #6 petersw, Jun 1, 2016
  7. SFO

    SFO Senior Member

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    Which garage did you take it into, and are there any updates worth sharing?
     
    #7 SFO, Mar 23, 2018
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  8. petersw

    petersw Junior Member

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    Actually, the story turned out to have a happy ending. I found out (through the great folks at Lucious Garage in SF) that the catalytic converter has a 150,000 mile warranty on it. So I brought the car to the Toyota dealer, and the converter was replaced at no charge!
     
    #8 petersw, Mar 23, 2018
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  9. JC91006

    JC91006 Senior Member

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    Good News! I didn't know it was 150,000 miles, I thought there was a time limit. Maybe it's 15 years/ 150,000 miles
     
    #9 JC91006, Mar 23, 2018
  10. padroo

    padroo Senior Member

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    I assume the car is still burning oil?
     
    #10 padroo, Mar 23, 2018
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