If you get a PD0455 check engine light, how do you fix it?

Problem scenario
You received a PD0455 check engine light. How do you resolve it?

Possible solution

1. Tighten the gas cap.
2. Clear the code (if you think you can otherwise ignore it). It may or may not be advisable to clear the code depending on what is actually wrong.
3. Drive the car as normal.