P0420 NISSAN - got this code, replaced catalytic converter, light still comes on

Question

Got P0420 code on 2004 Nissan Frontier XE 4 cyl 2wd. Replaced catalytic converter and light came back after erasing code. What next?

Answer 1

The factory suggest replacing the front O2 sensor when replacing the catalytic convert, also they suggest to reprogram the Engine Control Module (ECM). We suggest to reprograming the ECM before replacing the sensor.