2012 Ford Focus SE non flex po420 code replaced o2 sensor

Question

I have a po420 code on my 2012 Ford Focus SE non flex. I just replaced the upstream o2 sensor and the light came back on about 30 miles after the replaced o2 sensor. any suggestion's will be greatly appreciated. thank you

Answer 1

Hi there,

If there is a bad O2 sensor causing the issue it would be the rear sensor. Typically with this code you will have to replace the converter. In the US this is covered by an 8yr/80000 mile warranty and would be replaced by the dealer at no cost.