Question about 1997 Chevrolet Astro

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What is PO420 code

My 97 astro failed the emission test under this code po420, can you tell me what it is? Is it catalytic converter related problem and I need to replace it?

Thank you for your assistance.

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  • Anonymous Dec 20, 2008

    chevy tahoe



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It sounds like the catalytic at bank one where the number one cylinder is might be bad but it could be the 02 sensor also
have the catalitic test or removed from a mufler shop and have them inspect it iside for damage
if it is bad then replace it,
you can also top on it if you hear like little rocks inside that means is not good and must to be repalced

Posted on May 29, 2008


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