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P0430 Code Puzzle

Discussion in '1st Gen Tundras (2000-2006)' started by jsazc777, Sep 26, 2022.

  1. Sep 26, 2022 at 5:25 PM
    #1
    jsazc777

    jsazc777 [OP] New Member

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    I have a 2003 toyota tundra with a P0430 code, catalyst system efficiency below threshold bank 2, that will not go away. I have replaced both O2 sensors with denso brand while the negative terminal was disconnected. I replaced the catalytic converter on the passenger side. Erased the code several times. Drive the car 20-30 minutes and the same code throws the check engine light on. Any ideas where the code could be coming from?
     
  2. Sep 26, 2022 at 5:55 PM
    #2
    shifty`

    shifty` Is the Gila Copter a love machine?

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    '06 AC Limited V8/4WD
    (see signature for truck info)
    This is one of those cases where I'd prefer to have live readings to see what the O2 sensors are seeing.

    I hate to ask b/c we crank this so much, but you didn't happen to buy the O2 sensors on scAmazon, the king of counterfeit parts, did you?

    Which cat brand did you go with, b/c other members have found issues with certain brands?

    Have you traced the wiring on the passenger side to verify it hasn't been spliced or cut at some point for either sensor?
     
  3. Sep 28, 2022 at 12:54 PM
    #3
    jsazc777

    jsazc777 [OP] New Member

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    Thanks for the response.

    AP Eastern Emissions catalytic converter with both up side and downside Denso O2 sensors.

    Both bought through Rock Auto. Both look like original packaging.

    Anyway the MAP sensor would play a role in P0430 code? Any other ideas other than take to the dealer to hook it up to their computer?
     
  4. Sep 28, 2022 at 2:18 PM
    #4
    shifty`

    shifty` Is the Gila Copter a love machine?

    Joined:
    Jun 20, 2020
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    #48239
    Messages:
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    ATL
    Vehicle:
    '06 AC Limited V8/4WD
    (see signature for truck info)
    Not sure on the MAP sensor, but I kinda doubt it.

    At the most basic level, P0430/P0420 are bank specific. If I recall correctly, your pre-cat O2 measures the result of combustion (exhaust the output mixture), then the post-cat O2 measures it again after passing through the cat. If the difference in mixture isn't "clean" enough in the ECU's opinion, a P0430 or P0420 code is thrown, which code you get is depending on which bank (/cat) is not performing well enough.

    Most likely cause is either an incompatible cat - these trucks have a lot of issues with non-OEM cats, there's a small few that are "compatible" and won't throw codes - or it could be one of the O2 sensors (I'd suspect the rear) has damaged wiring, or is defective, gummed up, or damaged in transit or install.

    The no-cost-except-busted-knuckles approach would be to swap your front and rear O2 sensors from bank 1 to bank 2 and reset codes. If you see the code returns, but it switched from P0430 to P0420, you may have an issue with one of those O2 sensors. Next step is to switch just the rear from bank 1 to bank 2 and reset codes, leave the fronts in place. If the code switches again from P0420 to P0430, that would signal your rear O2 is probably the problem. If it doesn't come back within a week or two, swap the fronts over, and wait to see if a code pops. If it does, your front sensor is likely the problem.

    If you swap both O2 sensors from side to side and find the issue doesn't follow, I'm suspecting your issue is just your Tundra not liking your aftermarket cats. For compatible cats, users here have had good luck with Magnaflow, Summit Racing's "performance" cats. Not sure about others, these are just the two I've heard people install and go for years without throwing a code.
     

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