How do you fix trouble code P0420 on a 1997 ford tbird?

Trouble code P0420 indicates a problem with the catalytic converter's efficiency. To fix this issue on a 1997 Ford Thunderbird, first, inspect the exhaust system for leaks and ensure that the oxygen sensors are functioning properly. If the sensors are fine, you may need to replace the catalytic converter if it is indeed failing. Additionally, clear the trouble code and conduct a test drive to see if the code returns.