P0455 Chevrolet -

Question

I have codes P0455 and P0442 on 2010 chevy silverado. I tested the gas cap and it passed gas cap leak check. What is the next most common thing to check???

Answer 1

Hi there,

The most common issue would be the vent control valve. The P0442 is for a small evap leak while the 455 is for a large leak. If there is a big one, then there is going to be a small one first. If the vent valve is stuck open it will cause both codes.