I was wrong with my first post.

Reading over the DTC troubleshooting chart (Honda manual) you really will need to leave this to a good technitian with the proper tools.

Tighten the gas cap as much as you can, the code will still come.

good luck from here

 

Sometimes all you can do is

 

Take this to the bank yo

1456 is for a loose cap.

 

I had p1457 when the car was new, it required replacement of parts, it was most definitely not a loose gas cap.