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P0420 and P0430 code questions

Discussion in '4th Gen 4Runners (2003-2009)' started by MadPainter, Feb 1, 2019.

  1. Feb 1, 2019 at 1:05 PM
    #1
    MadPainter

    MadPainter [OP] New Member

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    Hello, I recently purchased a 2007 4runner SR5, V6 with about 180,000 miles. This is my first 4Runner and I like it a lot. But I'm also getting some DTC codes that I'm trying to fix. I'm trying to do most of the work myself since money is tight.

    Using the BlueDriver app and scan tool, I am pulling DTC codes of P0420, P0430, P0456, and C1201. A month ago I was also pulling a P0455, P0441. I replaced the gas cap and the P0455 and P0441 have gone away and not returned. Other than that, there are no other codes detected with BlueDriver.

    I have searched posts on this forum and others and am starting to get a better idea of the situation, but I still have questions.

    I am mainly concerned about the P0420 and P0430 codes right now.

    1) How can I be sure that I really need to replace the cats?

    2) If the cats are actually bad, do I need to replace all four, or just the two that have the O2 sensors?

    3) I can't figure out what might have caused the cats to go bad. I don't want to replace the cats again in a couple of years because I didn't address the underlying problem.

    4) If my vehicle has a sticker that says it is California compliant, do I need to replace the cats with California cats? I live in CO, which I don't think is currently a CARB state.

    5) Is replacing the cats a realistic DIY job? It doesn't look like a very complicated procedure other than possible frozen fasteners. I'm fairly handy and have a decent set of tools, but I'm also just learning to work on vehicles.

    Here's more info that might give a better picture of the situation.

    - Live Data shows that O2 sensor 2 in both banks fluctuates widely from about 0.1V to 0.8V and trails the first sensors by about a second.

    Freeze Frame Data recorded after error code P0430:
    STFT Bank 1 = -1.6%
    LTFT Bank 1 = 0.8%
    STFT Bank 2 = -3.1%
    LTFT Bank 2 = 2.3%
    Engine RPM = 1680 rpm
    Mass Air Flow Rate = 35.60 g/s (4.71 lb/min)
    Cat Temp Bank 1 Sensor 1 = 1410.3 F
    Cat Temp Bank 1 Sensor 2 = 1196.4 F
    Cat Temp Bank 2 Sensor 1 = 1410.3 F
    Cat Temp Bank 2 Sensor 2 = 1196.4 F

    There are lots of other measurements I can provide if needed.

    - The dealer replaced Bank 1 O2 sensor 2 at time of purchase two months ago. I'm not sure if this was a new sensor. I have since come to doubt the honesty of this dealer as several “fixes” they supposedly made to the vehicle turned out to not have been correctly (that's a different story).

    Thank you for taking a look at my post.
     
  2. Feb 1, 2019 at 2:15 PM
    #2
    MattAK

    MattAK t4r.org refugee

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    Utah
    Vehicle:
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    Fixed broken shiz. Dobinson's 2.5"
    Mine's a V8 but I started getting P0420 a couple of weeks after I bought it last year. Replacing the downstream O2 sensor seems to have solved my problem, the code hasn't come back in the last several thousand miles *knocks on wood*.

    It's hard to know exactly. Things I read said temp differences between the two sides, smelling the sulfur/rotten egg smell, bad fuel economy. If you smell fuel like the truck is running rich that could have ruined the cats.
    The downstream O2 sensor is between the two cats on each side. when I was researching this issue for my V8 I normally saw people only replacing the first cat.
    I know you can ruin cats if you're running too rich but not sure of other reasons.
    You only need CARB compliant stuff if you live in or are planning to move to California. Does CO do emissions testing?
    The upstream cats are welded onto the exhaust headers, so it's DIY if you can cut them out yourself and weld new ones in, or feel confident in replacing your headers. Personally I was mentally prepared to pay a shop to replace mine if the O2 sensor didn't fix it.

    O2 sensors fluctuate their voltage normally. Doesn't mean they're not bad, just that fluctuating voltage is normal rather than a symptom of something wrong.

    If the truck is otherwise running normally, you don't have crappy fuel mileage, and you don't have to worry about emissions, then you could just get a couple of cheap O2 sensor spacers.
     
  3. Feb 2, 2019 at 6:02 AM
    #3
    MadPainter

    MadPainter [OP] New Member

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    MattAK, thanks for the info. As far as I can tell my 4R isn't running overly rich or lean since the LTFT is less than 5%. But I am just now learning about this stuff, so it's possible I'm missing something. Plus it seems to run fine and I'm getting about 18 mpg on average around town. It's possible that the previous owner already addressed any tune-up issues before they sold it.

    Yes, CO does require emissions testing. Right now, CO is not CARB compliant, though they recently passed legislation requiring compliance by 2025. So it sounds like I should be OK for now with non-CARB cats. I'll confirm that next week when the facility opens. I'll also do some digging into the O2 sensors.

    Thanks.
     
  4. Feb 3, 2019 at 8:33 AM
    #4
    Old Man 4x4

    Old Man 4x4 New Member

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    Hello, I'm new to this forum, but quite adept at catalytic converters. It would be my advice to replace the cats with CARB compliant cats. The amount of precious metals are much higher in the CARB cats to make sure the light stays off. And as long as the light is on, the vehicle will be running in an enriched circuit, which will cause you fuel mileage and other issues as time goes on. As an alternative to replacement an old trick used by Subaru is to remove the cats, block up one end, and soak the substrate in lemon juice. This removes a soot build up which causes the cats to not light off properly. To give you a little background info, I worked in the exhaust industry for 41 years, as a manufacturer's rep, a warehouse owner and a muffler shop owner.
     
  5. Feb 3, 2019 at 9:31 AM
    #5
    MadPainter

    MadPainter [OP] New Member

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    Old Man 4x4, thanks for the info. I had heard that bad cats would eventually affect the running of the vehicle. Didn't realize it was through the fuel trim. Does that explain the negative percentage on the STFT? I have also seen some youtube videos where people have washed cats in various solutions, some with success, some not. In your experience, do cat cleaners work? The marketers definitely promote them hard, but it seems like it might work better as a preventative rather than a fix for a cat that's already bad. Thoughts?
     
  6. Feb 3, 2019 at 9:39 AM
    #6
    MadPainter

    MadPainter [OP] New Member

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    OldMan 4x4, another follow up question since you've worked in the muffler industry...am I correct in thinking that a fairly handy person could replace the cats themselves with bolt-in cats and a fair amount of elbow grease, time...and rust solvent? I don't have the setup to weld anything so I'd have to use cat replacements that bolt in to the manifold. Thanks
     
  7. Feb 3, 2019 at 4:25 PM
    #7
    Old Man 4x4

    Old Man 4x4 New Member

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    Always clear the MIL before checking fuel trim. The vehicle runs "enriched" while the light is on to protect the engine. I have never seen a fuel treatment or "cat wash" that works by pouring it into the tank. Most treatments are petroleum based and can cause more soot on the cats substrate. The soot acts like an insulator over the precious metals, causing the cat to have difficulty reaching operating temperature, which, in turn, causes the trouble light. As for your being able to replace the cats, I don't see why not. Just be sure not to break the bolts up around the manifold. A muffler man despises correcting your mistakes. He makes enough on his own, LOL.
     
  8. Feb 3, 2019 at 6:13 PM
    #8
    MadPainter

    MadPainter [OP] New Member

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    I didn't know that about clearing the MIL and how that can affect the trim. Thanks for that bit. Also thanks for your input on fuel additives. They sure sound enticing because they seem so simple and inexpensive compared to a more involved fix. But I guess as often happens you get what you pay for. Yeah my biggest concern with doing this myself is breaking a bolt at the manifold. I'm hoping that using rust solvent and letting it sit overnight will help with that. Thanks again for your insights on this.
     
  9. Feb 6, 2019 at 5:42 AM
    #9
    blackoutt

    blackoutt New Member

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    Adventure Build
    Lots of PB blaster and patience will be your friend. And heat if you really get a stuck stud. Not sure if the V6 is the same but the V8 studs require a fancy socket to remove them and it's well worth it. Might as well replace the studs while you're in there.
     
  10. Feb 6, 2019 at 1:49 PM
    #10
    MadPainter

    MadPainter [OP] New Member

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    Thanks blackoutt. It does look like the studs might require a special socket. I will take your advice with the PB blaster and taking my time. I definitely don't want to break off a stud.
     

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