What does gas cap have to do with fuel tank pressure?

This was very enlightening. So apparently one of the items on the checklist for these inspections is the evap system; they found the tank didn't hold the pressure adequately and pinpointed the gas cap as the problem even though the light has not yet come on to warn me. Thanks so much.

Just in case the light does return , post the specific coe. The CVS (canister vent shut-valve) and the two-way by-pass valve and solenoid are two other common problems on this model. can involve a little time to properly diagnose which one (or both) is/are bad. Has your CR-V ever been bumped or hit in the fuel tank filler neck area? ..............HOPEFULLY it's just the cap! AND hopefully they replaced it with a Honda cap. I've seen a few aftermarket caps that don't function the same as OEM.

Thanks so much. Because the light has not come on yet, I was surprised and confused; your answer was very helpful in determining what to do next.