Question;


After changing plugs and coils (after misfire code)


I now get a P420 for catalyst.
I am betting it is the O2 sensor. But there is two if I am not mistaken.
Some parts places only list one, others list an "up stream" or "down stream"


How do you know which to change?

 

P0420 is the upstream sensor. Do a Google search on P0420 Honda Fit and you will see.

 

Thanks! That helps