If this is a California emissions certified Infinity there will be a catalytic converter just below the front exhaust manifold (this is the catalytic converter in front of the radiator) and the P0430 is indicating that this cat is either not working properly or there is a leak in the exhaust manifold or intake manifold for bank 2. Bank 2 is the side of the engine towards the radiator.
We recommend replacing your Infinity's catalytic converter only after inspecting the bank 2 rear oxygen sensor to ensure the oxygen sensor is not sending a lazy signal to the ECU (engine control unit). You should ensure the oxygen sensor is working and also ensure the oxygen sensor is communicating properly with the ECU.
