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P0420 Code

Discussion in '3rd Gen 4Runners (1996-2002)' started by 4x4Addict, Feb 28, 2017.

  1. Feb 28, 2017 at 3:07 PM

    4x4Addict [OP] New Member

    Dec 6, 2016
    First Name:
    Chico, Ca
    '96 4Runner SR5
    Magnusun Supercharger URD 7th Injector Yota1 Performance Rebuilt Motor OE Locker Suspension... Sound System... Bumper...
    Hi everyone,

    I need some advice. Coming home my CEL came on and I just found its the P0420 code.

    The code reader reads this: Catalyst System Efficiency Below Threshold (Bank 1)

    Now this is the second time this code has come up, the first was a few months ago but after disconnecting the battery (I was wiring a light bar), the light went away.

    This is a 96 sr5 with the v6 and it has close to 400k miles.

    I don't think the 02 sensors have ever been replaced and I know they are a wear item.

    I am thinking that one of them is bad instead of a bad cat but I wanted to run it by you all to get your 2 cents.

    Oh and about the time the code came up the first time I noticed my milage dropped from 17 to about 14 city.

    Thanks in advance!
    Last edited: Feb 28, 2017

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