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Thread: obd II code p0421 and p0431

  1. #1

    obd II code p0421 and p0431

    my check engine light came on and a buddy of mine has a "mac obd II " scanner, both codes read "warm-up catalyst effeciency below threshold bank 1 and 2 . i gotta pretty good idea what it might b but 2 make a long story short has any 1 here had a simalar problem. thanx.

  2. #2
    Most likely it's your catalytic converter, but it could be O2 sensors as well. Also, if you have headers that eliminate the hookup for the EGR tube to the exhaust, that throws the same code. Atleast it did for me.

  3. #3
    a DANJ , first thing i did was take it to a muffler shop because i suspected my cats and dude told me that it was not them according 2 the code i was giving him , 2nd i went 2 this mechanic shop thats been around 4 awhile after 1 hr and 69 bucks later that dude told me i needed a valve job, mutha fucker is nuts! so im thinking also sensor or 1st dude was wrong and it is my cats. Id like 2 knw if there is sum test i can perform 2 determine. thanx G

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