I have recently put a new head on my 02 zx2 and have had trouble with these codes. I have replaced the gas cap after the P0455 code. Today I got a P0457 code. I assume I have a leak in the evap system however I have no idea where to go next. I can't afford a smoke test as I live in a small town and the guy wants $150 to do one. I also don't know what lines go to what or where they are for the evap system. Can someone guide me through getting this resolved. Thanks.