OK, so I had this problem for several months on my gsr swapped 99 civic and couldn't figure out what the heck it was. I replaced almost all the EVAP system components that were shown in the EVAP diagram and checked all hoses for leaks. No dice!

Then, I read somewhere to check your PCV system for leaks or disconnected hose. WAHLAH! Hose for the PCV valve had come out of the grommet in the breather chamber. Plugged the hose back in and no more p1457. If you are one of the manyh that cannot find the problem with the EVAP canister system, remember to check your PCV system, may save you a ton of dough.

 

For some reason I don't buy that at all, many people reroute their PCV systems, and Honda does not have a sensor to monitor the PCV system, it is also not a part of the "EVAP" system. (It is EVAP related, but for blowby gasses, not fuel tank vapor.)

Most common cause for EVAP leaks is the gas cap. During normal driving it doesn't purge too often, but when a fault is detected, it can be hard to trace it to a specific time frame.