Check engine light came on. Diagnostic code P0420. Failed emissions. on 2005 Acura RSX

Is this a sensor or does the cat. converter need to be replaced altogether? Check engine light came on, code P0420, failed emissions inspection.

Asked by for the 2005 Acura RSX
In most cases when code p0420 sets the catalytic converter requires replacement. Please use the RepairPal estimator to find out what the cost should be. Here is a link - https://repairpal.com/estimator?car_type_id=4292