Arrogance is Oedipus's fatal flaw. Arrogance can be defined as thinking you are better than others and incapable of sharing their weaknesses. Before he literally blinds himself, Oedipus is metaphorically blind--blind to his capacity both to do wrong and to be wrong. Because of his arrogance, he can not conceive he might be responsible for the plague in Thebes. He cannot believe that he might possibly have murdered Laius, another sign of his arrogance. With even more arrogance, he forgets the stranger he murdered on the road. He is so sure he is incapable of wrongdoing that he forgets--or more likely represses-- a murder that would challenge his careful construction of himself as a pure, blameless individual.
Finally, rather than humbly accept the possibility that he could have killed Laius, he accuses Creon and Teiresias of conspiring against him by suspecting him of the murder. This would be plausible--people did conspire against rulers--but Oedipus doesn't bother to investigate because, in his arrogance, he is sure they must be wrong.