I have a '98 Nissan 200SX with the Check Engine light on. It keeps showing the P0440 EVAP emissions malfunction code. This has been a continuing problem with my car. When I first bought it, we changed some vacuum lines that were cracked. That turned the light off for a few weeks but it turned on right before inspection. We then changed the back O2 sensor (the front one was replaced by the previous owner). The light had been off all winter until now. I am not sure what else could be triggering the code. Any help would be appreciated. Thank you in advance.