I have have 3 codes page,p0455, p0442, and p0496 I'm on a 2005 cobalt

Question

I m trying to see if it's the purge solenoid valve or the fuel pressure sensor already changed gas cap

Answer 1

P0455 Evaporative emission  system large leak detected

P0442 Evaporative emission system small leak detected

P0496 Evaporative emission system flow during non purge

This is going to be the fuel tank pressure sensor , not reading right , it thinks there is pressure or a vacuum in the fuel tank , failing to report the true condiion if the fuel tank results in large leaks and small leaks