My 2002 WJ Overland with 4.7L HO engine has the California/50-State emissions system (4 oxygen sensors, 2 mini catalytic converters before the main convertor, no oxygen sensor after the main converter).
I'm getting a P0420 DTC, which according to the service manual and wjjeeps.com translates to "Catalyst System Efficiency Below Threshold (Bank 1)".
Question: which catalytic converter is this referring to? I'm assuming it's one of the mini converters since it refers to "Bank 1".
Thanks everyone for your help!