2006 silveado 4x4 already replaced with factory gas cap next suggestions

Question

Already replaced gas cap w let pàft what is your next suggestions

Answer 1

P0455 Evaporative emission large leak detected

Is this the only code that show, there is no P0496 which is a Evap vent control canister purge? With a EVAP that has a large leak detected this is usually found by doing a visual , beside a evap smoke machine, and you can even smell raw fuel. It is the FTP (Fuel tank Pressure ) sensor when it comes to a Chevy product that always is suspected as being faulty.which is located at the top of the fuel tank module