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Old 10-25-2010, 05:03 PM   #4
clinebarger
Senior Member
 
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
Re: Codes P0420 and p0430

DTC P0420
Catalyst System Low Efficiency Bank 1

DTC P0430
Catalyst System Low Efficiency Bank 2

Check the post catalyst 02 sensors for wiring damage.

Check for exhaust leaks.

Things that can degrade the catalyst itself..

An engine misfire
High engine oil or high coolant consumption
Retarded spark timing
A weak or poor spark
A lean fuel mixture
A rich fuel mixture

Its hard to believe that both catalyst went bad at the same time, so check it over real good.
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