1997 GP, SE, 3.8 DTC Code P0420 (HELP)

My SES light continues to come on and I had it read at Autozone and It gave me the code P0420 which means "Catalyst Effiency Below Threshold". What does this mean? What needs to be replaced? The guy at autozone said that anything can spring that code. He recommended that I take it to an auto repair shop and have a real Diagnostic test done to it. What do you all think? Or does anyone have any experience with that code.



Thank you

It could be a problem with either the rear O2 sensor or Cat.


~Larry~

probably means that you need a new catalytic converter.