I got a P0420 code meaning I had a bad catalytic converter

Was the catalyst replaced? If not then a reset won’t work.

Site error.

It's very simple... You fix the problem. Replace the catalytic converters and maybe O2 sensors as well. This is one of my favorite cars, and yours in average condition is likely worth no more than four grand. If you want to continue driving this car, repairs might be as high as two grand.

Google P0420 fix. Companies sell spacers for the downstream O2 sensor. I pulls the sensor out of the exhaust stream and fools the computer into think the cat is good. The use a scanner to clear the codes. The smog test won't pass if all the monitors are not set. You need to run drive cycles to set all monitors.

Those spacers don’t always work. Sometimes they cause drivability issues.

Tampering with the emissions systems is illegal. Adding spacers is considered tampering. The only way to fix a P0420 code is to replace the catalytic converter. However you must know what emission control system you have. Is it California emissions, Federal emissions, northeastern region emissions, etc.? The emissions decal under the hood will tell you. Replacing the catalytic converter with the wrong one will only cause the P0420 to come back. Another thing to keep in mind, especially considering the age of the vehicle, is usually something else causes the catalytic converter to fail. Misfiring, the number one cause of catalytic converter failure, or burning oil, or coolant leaking inside of the engine. Before you spend the money to replace the catalytic converter, make sure everything is good with the engine. Jim