my mother also has a 2003 lancer oz and she has been having issues with the cel coming on every time we have it read it comes up with code 456 (small evap leak).
she was told it was prob her gas cap... she bought a new one and still gets the CEL.
she brought it to a garage and they used a machine and put smoke through her evap system and they found no leaks. we and the machanic are stumped now
I figured I would ask here and see if anyone happens to have any ideas or if someone has dealt with this before.