Sorry to open up an old topic (thanks to google), but I too am getting the same P1457 error on my 2002 Acura 1.7EL and im wondering it you guys have fixed the problem?
I've already changed the EVAP shut valve (VSV) attached to the charcoal canister under the car, and the code hasn't gone away. (I didn't reset it with my scan tool yet as I was hoping the computer would clear it itself now that the part is fixed.). So my next step is to maybe take off the Purge Valve located at the front of the car and spray some TB cleaner or WD-40 in there to free things up as what MTL_4runner did, and see if that works. If im still not solving the CEL problem, then ill buy the other valve located beside the charcoal canister called the 2-way Bypass solenoid valve. Apparently this is one of the main problems causing this P1457 issue according to internet searching. MTL_4runner mentions this valve, but never said if he replaced it or not. I have the Honda "Service Bulletin" infront of me (08-016) "MIL Comes On With DTC P1457" and it explains how to diagnose and replace this solenoid. You can download it here...
http://ww2.justanswer.com/uploads/ac...t_solenoid.pdf
Im located up in Ontario Canada so yes my car is subjected to the salted roads. I've got about 290K km's on it and the light only recently came on. Luckily the previous owner Krown rusted proofed it most of its life, so it doesn't look too bad. The screws and bolts around the EVAP system were rusted but a good shot of PB blaster really helped. Since the CEL light came on, my gas mileage has decreased quite a bit....about 150-200 km per tank!! Not sure if it pure coincidence or what. I've checked the sparkplugs and air filter...all is good...
I'll write back with updates, perhaps it will help someone else who is experiencing the same issue. Thanks to MTL_4runner for his updates in the past on this issue... Very detailed which is hard to find on the net these days. Hopefully he chimes in and gives me an update on his car. Perhaps he's already got rid of it! lol