2012 tacoma trac off and engine light and av gas code p0430

Hello, pulled the codes and got a p0430 . Catalytic system efficiency below threshold bank 2. That doesnt sound good, anyone ever run into this? possible fix other than dealer? would this affect gas mileage?

 

ok after some digging found out its either oxy sensors or cat. question is the upstream an oxy sensor or an af sensor? downstream of cat would be a oxy sensor?. the other day i put in about 10L of av gas 100LL mixed with 89 oct fuel. i think the lead in the av gas may have coated sensors. anyone know of an additive i could add to the tank to remedy the situation?