Urgent is trouble code PO420 on a 2000 camaro bad??

[drift95]

I just sold my 95 LT1 M6 T/A and picked up a really nice 2000 black and white B4C Camaro THREE days ago and the SES light went on while in traffic. I went to Advance Auto Parts and used their scanner and it said: Check engine code PO420: Catalyst System Efficiency below threshold (bank 1). I reset it and drove it two miles and it didn't come back.Is this just a O2 sensor/cat. converter "normal" code or am I in trouble? PLEASE HELP because I just dropped every dime I have into buying this thing and am not looking to put gobs of money into it....any body have this issue?

Also I noticed that the SES light will sometimes not come on dunring a key on situation.....related??

[Aldo]

I used to get that same code on my truck. I had a bad gasket at the joining of the catalytic converter and the tailpipe. I changed it and it went away. Then months later it came back and it was the converter itself that went bad. I had 167,000 on it and it started cracking. The converter was replaced and that code was gone.

Start off with the cheapest thing. Look for any leaks. Then check o2 sensors. Lastly it would probably be the converter.