I've had this error code for weeks now... I just went to autozone and replaced the gas cap, as this is the easiest and most common cause for the error code. My check engine light is still on. I was told I don't have a leak at the engine/motor or at my fuel tank, so its most likely a hose under the car. What could be causing this problem?

1998 Accord EX V6 3.0

 

Take a look in the DIY section; search for "P1456" you should find a post by me.