Is it OK to receive Communion if the priest has accidentally or otherwise changed the words to the consecration of either species. A situation like this has happened to me twice in the past few months! Also, would a Mass like this fulfil my Sunday obligation or do I need to attend another Mass?
Masses are neither valid nor invalid. Only the consecration is considered valid or invalid. Canon law prohibits the priest from changing the words of the consecration. But if the priest does so anyway, so long as he conveys what the Church believes in consecrating the elements, the consecration is valid. The Church is flexible in this for the spiritual benifit of the faithful. So you did fulfill your Sunday obligation.
Fr. Vincent Serpa, O.P.