1997 Ford TBird 4.6 Code P0420

Question

I have the ob11 reader. My 1997 TBird is showing a po420 code. I have replaced o2 sensors in the past on this car, always on bank 1,usually upstream I believe. If the plugs are ok and the injectors are clean should I try switching the sensor from bank 2 to see if the problem goes away?

Answer 1

P0420 Catalytic below threshold Bank 1

If the front 02 sensor does not work properly neither  will the catalytic convertor, what the upstream does is maintain fuel control. by comanding a lean to rich signal as long as there is no problem affecting the air to fuel ratio.. and this is how the catalytic convertor works. You can swap the front 02 sensor and do a MAF airflow cleaner and look for any vacuum leaks especially at the PCV hose which usually has a tendency to rupture overtime.