I had this same issue, still coding P0420, with a new cat. But it was aftermarket, and was too small. A larger 1 solved the problem. I have never had a bad o2 sensor set this code on a Honda, just a bad cat.
I had this same issue, still coding P0420, with a new cat. But it was aftermarket, and was too small. A larger 1 solved the problem. I have never had a bad o2 sensor set this code on a Honda, just a bad cat.