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P0420 Catalyst System Efficiency Below Threshold

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by t0y0taprius, Aug 29, 2022.

  1. t0y0taprius

    t0y0taprius New Member

    Joined:
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    2005 Prius
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    DA78C00A-A45F-4A7A-9A51-681EAC447D41.jpeg E7CDDDF4-6E94-4A83-9842-DBD4C04601CC.png
     
  2. bisco

    bisco cookie crumbler

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    does that mean you need a new cat?
     
  3. Tombukt2

    Tombukt2 Senior Member

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    Pretty much a new real cat from Toyota none of the aftermarket ones I put on can clear the code they're okay on the sniffer but they won't clear the cars code so I don't know how that works exactly but cool enough. I've just left my coding cat in place and I've just had it checked on the sniffer two or three times to make sure that it's clean and within spec but if I turn the light off it comes back within 48 hours. So we're just going to leave it if I ever take the dash apart again I'll just take the check engine light LED out it's been on for 2 years nothing's ever come of it except the cat below threshold anytime anything else is wrong the check engine light has pretty much nothing to do with it it's all the other lights I have been round and round with this for the whole 2 years my check engine light has been on when my battery failed when my ABS failed etc the check engine light didn't do anything. And looking in the history of the check engine light when I was having all those problems apparently it wasn't even being turned on from all the battery codes and all the ABS codes when I would go to check those text stream wouldn't would say the mill light was on because it was already on for the cat below threshold it didn't set the mill light on because the ABS failed of course it was already on but in the computer print out it would tell me that the mill light had been set by the ABS or the battery going bad and I didn't see that.
     
  4. SFO

    SFO Senior Member

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    Is that the actual ODO reading after 17 years?
     
  5. bisco

    bisco cookie crumbler

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    wow, that would have my 2005 dakpta beat by 13,000 miles!