Hi my engine check light is an my catalytic converter is messed up so wat do i go buy bought fixing it

well, try cleaning it first as in this video. if that doesn't work, get an aftermarket cat from a company like Walker, they work fine and cost lots less https://www.youtube.com/watch?v=5icTmYItwiE&t=3s

Hey Scotty ... what is the fluid u put in petrol tank ?