2000 Chevy S-10

Hi, Sometimes the dealer can reprogram or update the computer for this code. If their is a update. Most Of the time there is not. On on Some cars.(99% of the time it's the catalytic converter going bad.I'd stay away from aftermarket cat. Converters, yes they are cheaper, but some are not up to factory specs. Also Not all Fit right, they have to be welded into the system. And you put them on, and a month or so the light is on again with the same code po420. The dealer catalytic converter is much more expensive. But less problems with them. So weigh out the cost, versus time.

Hope This Helps You,
Good Luck
Edward S.