I have a 98 accord sedan 2.3L and the check engine light came on with a p1456 code, i know it is an evap system code but not sure where to start. I cleared the code and it came back on within 20 miles of driving. the gas cap is not loose i checked it multiple times. Thanks.

 

Hope you have a manual and time.....

Might read thru this post for some ideas of testing and such, along with the steps in the manual....
honda-tech.com/showthread.php?t=2639636&page=2

 

thanks ill definately look at that.

 

I have the same exact code. Mine however is a leak in the gas tank. Fill up your tank to about 3/4 full and park it (maybe overnight). Check to see if there is any fuel leakage under the car. If there is thats the cause of it. Worse part about this is that if the crack or leak is near the top of the tank its costly as you have to drop the tank down to fix it.
Best of luck

 

i had this exact problem as well and i fixed it quit easily. Before you get into doing alot of work to fix this problem, buy a new gas cap and replace your old one. Its a quick fix to this problem. Sometimes (over 14yrs worth of time) the gas cap gasket gets old and cracks and cant provide the necessary seal and the car recognises it as being below threshold and pops a p1456 code. Its a quick fix and it worked for me! Before you start replacing anything (possibly the evap cannister) spend 10$ and c if its just your gas cap. Its just a possibility...

good luck, let me know how it goes!