I disagree, different orders of paladins would have different codes by which they live and behaviors that could be expected of them, all a paladin code has to be is a lawful good code that the character has chosen to live by.
that said, for a generic paladin i allways use the old no chaotic acts, no evil acts or you lose your class abilities (DM discusses with player the motivation behind questionable actions, decides if the act was truly chaotic or evil and decides if there can be attonement or not, his decision is final). nobody seems to play paladins in my campaigns, perhaps i am to harsh due to my dislike of religion based campaigns.