P0455 Chevrolet -

Question

emphasized text Can you tell me what should be replaced ?

Answer 1

P0455 Evaporative emission control system Large Leak detected

Fuel cap not sealing can be one of the cause, large tear in the filler fill hose , or the FTP (fuel tank pressure) sensor not reporting the correct pressure.

Some of the most common cause for a EVAP leak code whether large leak or small are the fuel cap not properly secured or just missing

Another cause for a P0455 would be a large tear , here is a fuel filler hose with a rip in it.