P0420 2006 Toyota Camry -cel comes on ten goes off passed nys inspection

Question

this is a 2006 camry 4cyl i cleared codes then drove 80 miles all differant kind of driving 40 50 60 70 start an stop many times started eng many times my wife took car out and the ck eng came on then about 15 miles of local driving the light went out . Took car in for inspection nys and it passed car still shows code on scanner but no check eng light ?????? also my scanner actroncp9180 shows evap system inc even after all that driving code po420 1of1 catalyst efficiency below threshold bank 1 what is the problem ??????? thanks

Answer 1

I would start to use 91 octane fuel from shell, and maybe do any intake flush with seafoam or 3m to clean out the valves and carbon built up