infiniti 2003 Q4 is reading po420 and also p158 and po420 with a pd at the end of that

Question

had a muffler leak so i fixed that now reading po420 and p158

Answer 1

P0158 - 02 sensor circuit high volage (Bank 2 Sensor 2)

P0420 Catalytic below efficiency threshold (Bank 1)

Circuit high code such as P0158 are disconnected sensor, Here you  have a sensor 2  which is a downstream 02 sensor or the catalytic monitor sensor.of Bank 2, This 02 sensor is more than likely a disconnected 02 sensor,Since the muffler has been repaired was it disconnected for any reason?  Restore Sensor 2 or code P0158 and retest the vehicle if P0420 reappears more thn likely you will need a catalytic convertor for Bank 1