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P0421 on a SIlverado 1500 5.0 engine 1998

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3 years 4 months ago #45824 by Batiscafo
This Chevy Silverado 8 Cyl. 5.0 with 238,000 miles started to throw P0421 on my last 1,200 mile trip.

How should I hook up the Picoscope and try to understand what is going on; be 02 sensors, wiring or just the bank 1 cat?

I only have two channels on my 2205 A plus all attenuators.

Thanks

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