Answer by taking a quote from the following article:

Dr. Victor Von Doom (commonly known as Doctor Doom, or simply Doom) is a fictional character appearing in American comic books published by Marvel Comics. The son of a Romani witch, Von Doom has been depicted as a supervillain, the archenemy of the Fantastic Four, and the leader of the fictional nation called Latveria. While his chief opponents have been the Fantastic Four, he has also come into conflict with Spider-Man, Iron Man, Black Panther, and multiple others. Von Doom has also been depicted as a superhero, being the third character to take up the mantle of Iron Man and joining the Avengers.

On many occasions, Doom's only real weakness has been his arrogance. Layla Miller once reflected that Doom is incapable of accepting that he himself might be the reason for his failures. This is most keenly reflected in Doom's continued refusal to accept responsibility for the accident that fully scarred his face, instead preferring to blame Reed Richards for sabotaging his experiment. While his high opinion of himself is generally accurate, he is generally unable to accept when others may have a better understanding of a situation than he does - with the occasional exception of hearing the recommendations of heroes such as Mister Fantastic or the Thing when it is to his advantage. Even when teaming up with others against a greater threat, Doom will often try to subvert the alliance for personal gain. For instance, while allied with Adam Warlock and other heroes against the Titan Thanos, he attempted to steal Thanos' Infinity Gauntlet before its owner had been defeated.  Von Doom adheres to a strict code of honor at all times. However, Von Doom will keep his exact word, which may or may not be beneficial to the person to whom he has given his promise. For example, Doom may swear that he will not harm an individual, but that only means he will not personally harm that person; it does not mean he will prevent others from harming that person.  Doom's honor code led him to save Captain America from drowning because Captain America had earlier saved his life, and on another occasion he thanked Spider-Man for saving him from terrorists attacking him in an airport by allowing him to leave alive despite Spider-Man subsequently insulting him. His code of honor also means that he will not attack a respected opponent who is weakened or at a severe disadvantage, as he regards any victory resulting from such circumstances as hollow and meaningless. He has even on several occasions battled opponents who were intent on killing the Fantastic Four, for no other reason than the fact that he does not want the ultimate defeat of the Fantastic Four to come from anyone's hands but his own.  Victor von Doom has been shown to be devoted to the welfare and well-being of his subjects. Once, he even went so far as to let his soul lay bare and be judged by the Panther God of Wakanda, who determined that he genuinely wished for a utopian future where humanity thrived,

What other codes of honor did he have
His code of honor also means that he will not attack a respected opponent who is weakened or at a severe disadvantage,