Does the Church still teach you have to go to confession before receiving Communion?

Your pastor may say you don’t, but canon law says you do—at least if you know you’re guilty of any unconfessed mortal sin. According to canon 916,

A person who is conscious of a grave sin is not to celebrate Mass or to receive the body of Christ without prior sacramental confession unless a grave reason is present and there is no opportunity for confessing; in this case the person is to be mindful of the obligation to make a perfect act of contrition, including the intention of confessing as soon as possible.