GMC Sierra P Codes (Powertrain) P0400 - P0499 P0420

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1999 GMC Sierra Diag Code P0420

1999 GMC SIERRA
I Used My Programmer To Get Code P0420 And So I Took It To A Midas To Have Them Take A Look. The Guy Told Me That I Needed To Replace My...
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Asked by skelix912

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