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International Automotive Technicians Network
Re: Catylist Failure Code P0420
Posted to Technical Discussion Forum on 4/17/2002

Hi Nicholas,

Just to add to what Robert has said already. The catalyst code will only set after the monitor has run. If the ECM has not run the catalyst monitor then it will not set a code. Do you have a scanner that allows you to see monitor status? Hope th... Login to read more.