po420 code twc?

[MAXIMUS_PR]

Hey guys after selling my 92 240sx/sr20det 3 years ago i'm back again but this time with a 96 240sx stock that i plan to modify later,well back to the thread yesterday i pulled the codes because the check light was and it came 0325 knock sensor(of course) and 0420 TWC Function RH Bank waht exactly this code means and what can be done to fix it

[Cone Junky]

P0420 is a catalyst efficiency code. In aother words, the ECU has determined your cat is not working properly.

It might just be O2 sensors failing, but that usually throws a seperate code.