Will bad gas give a false po420 code on a 2003 Toyota Camry 2.4

Question

The reason I ask is that everything was fine until I fill up at this station an drove about 20 miles. And then the check engine light came on.

Answer 1

Most likely the catalystic converter is bad, if you alway fill up low octance gas that is a consequence over time, not just one time. Erase the code when you are at quarter thank and fill at least 91 octance and drive and see if the code goes away