I had a P0420 OBD code trigger a CEL on my 02 S2000 with 125000 miles on it.

P0420 = Catalyst System Efficiency Below Threshold (Bank 1)

Is it likely that I will need a new cat converter?

If so, would now be a good time for an aftermarket exhaust system replacement? Would this be cheaper or as expensive as an OEM cat replacement with better power?

Just offhand, what are the consequences of not replacing the cat? Failed inspections?

 

Well your gas mileage will be krap.. And its not good having a solid check engine light on.. what if something welse goes wrong???I have had this code before as well and it was because of raw fuel being dumped into my exhaust (don't ask).Whick inturn F@&^' the cat up.. If you don't want to go and buy a whole new exhaust or new oem cat.. then just go and buy a test pipe with a CEL fix.. Or if the one you choose does not have a a built in CEL fix the just go and buy some spark plug anti-fouler kit and make your own.. Look into a berk test pipe.. they have CEL fix built in I believe and they actually give some power too..

 

What state u live in.Make sure what u do is smog legal or u'll end up doing it all over again.

 

Good call.. I'm luck where I live... We don't have any emmision rules really

 

you can try to "revive" the cat...might, might not work. I have done it before and it will put the problem off for a little longer.....You will need to unplug a coil, going to the spark plugs, and create a miss. Hold a high idle (2k) for about 2 minutes then let it drop and plug the coil back......now clear the miss code. The burning gas enters the cat causing the cat to run super hot "reviving" it! Might or might not work....it's just a band-aid...