Question

On my 1998 Chevrolet Blazer 4.3L, how do I fix the engine code P0420?

Answer 1

if there are no exhaust leaks or engine performance issue most likely the catalytic converter is bad

Answer 2

P0420 Chevrolet Code - Catalyst System Low Efficiency Bank 1
Read more: https://www.autocodes.com/p0420_chevrolet.html