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infamous P0420 code

Discussion in '1st Gen. Tacomas (1995-2004)' started by KID3, Apr 20, 2011.

  1. Apr 20, 2011 at 8:18 PM
    #1
    KID3

    KID3 [OP] Well-Known Member

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    las cruces NM
    Vehicle:
    01 DC taco 4x4 sr5 trd
    lots
    So i got the infamous P0420 code today. i know that it is either a bad cat, the O2 sensors or a leak somewhere in the system. so my question is how long can i drive the truck before this needs to get fixed or before i ruin something else?

    Its a 2001 4x4 3.4L DC
    i have just went over 100,400 miles.

    was thinkin of just running some fuel stablizer and some different fuel to see if it goes away and also gonna take the sensors off to see how they look.

    Another question i read on here that is the cat is bad it is crazy expensive to relpace, so i was thinkin of guttin it and gettin the URD O2 sensor bypass. what are your oppinoions on this.

    will post back up tomorrow with how the sensors look.

    Oh and i have not had any type of sulfur or rotten egg smell from the exaust.
     
  2. Apr 20, 2011 at 8:25 PM
    #2
    bellassaiw10

    bellassaiw10 Formally afroman5015

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    Do you have a K&N air filter ?? my problem was over oiling and the MAF was dirty
     
  3. Apr 21, 2011 at 7:39 AM
    #3
    KID3

    KID3 [OP] Well-Known Member

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    las cruces NM
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    lots
    I have a volant intake but that is a dry filter and it has been in the truck for almost two years now. So I doubt that could be the problem. I'm thinkin it's more of a bad sensor just need to borrow a voltage testor to test them
     
  4. Apr 21, 2011 at 10:18 AM
    #4
    DblCabMN

    DblCabMN Well-Known Member

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    Mpls, Minnesota
    Vehicle:
    03 DC TRD/LTD
    Bilstein 5100's all around - Toytec/Eibach 112-620 Coils, Wheelers 5-Pack+Wheelers 2"AAL. 33x10.5x15 KM2s - Siped on Summit Racing 84-5883 rims with 3.750 BS. 4.88s. Demello HD round sliders. Home built full skids. Home built front bumper. Plasti'd badges. Energy Susp. steering rack bushings. Sway bar delete. Deck plate mod. aFe Pro-Dry. Gibson exhaust.
    I'm an 03 v6 with the same problem. currently at ~100900 miles.

    P0420 was popping up every 5-100 miles for ~2000 miles. Ripped apart the intake and throttle body. cleaned EVERY surface i could inside the TB and the intake arm. Doused the MAF once in Brake Kleen let it dry and again in actual MAF cleaner. Threw on a new air filter.

    after the first 300ish miles on a very wet, humid, long drive it popped on again. and after clearing the code and 'goodish' weather >500 miles later, no return of p0420. Not saying it's gone for good. But i'm pretty dang sure i can get through the summer with only having to reset the code once or twice more.

    Goodluck!
     
  5. Apr 21, 2011 at 11:07 AM
    #5
    skytower

    skytower Well-Known Member

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    Dave
    virginia
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    Hitch and wiring, aux back-up light, rear strobe lights, radio and underseat sub.
    P0420 Catalyst System Below Threshold means that your cat is most likely going bad. Get your exhaust gas analyzed to confirm.
    The upstream O2sensor fluctuates with the fuel/oxygen mix in the exhaust. The downstream O2 sensor should not. When the downstream sensor starts to fluctuate, it indicates that the cat, or the sensor is bad.

    I would get the exhaust anaylzed to pinpoint the problem.
    Here's a more detailed explanation:
    http://www.aa1car.com/library/p0420_dtc.htm
     
  6. Apr 21, 2011 at 12:05 PM
    #6
    TallTacoma

    TallTacoma Bear fvcker!

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    Come and take it from my cold, dead hands.
    3" suspension lift (ToyTec coilovers and wheeler leafs), Yakima roof rack, ARE tonneau, K&N FIPK.
    I've been getting a random P0420 code for 15,000 miles. I noticed that it occurs when I'm very light on the throttle and driving for max fuel economy (low RPMs.) I clear the code with the Scanguage II and drive on.
     
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