Hello, I have a 98 Silverado with a 5.7(350), my service engine light keeps
coming on and always reads the same code, p0420 which means"catalyst system
efficiency below threshold (bank one)", I have one of those hand held
diagnostic scanners. I have changed both oxygen sensors on the drivers
side( I have a total of 4 on my truck) and I have used G.M. parts. I usually
get a day of driving before the light comes back on, then I clear it and
about a day later it is back on. The truck runs the same as it has always,
no difference in fuel economy and my catalytic converter is not plugged or
is any thing rattling in there, idles fine ect. Any info would sure be
appreciated, thank you........Ed

chang the cats with o.e. convertors. aftermarket convertors will not work
"Ed Atyeo" <eatyeo (AT) telusplanet (DOT) net> wrote