illegal en passant?
As said, would need to see the position.
Reasons why it would not be allowed. Capturing en passant results in putting your King in check. It is illegal because the pawn advanced only one square not 2 squares. If it moved 2 squares you did not capture immediately, but played another move/moves first, again illegal.
@RassadinCHess @Enriquito1234
Any move that follows the rules of chess and how the pieces are moved is legal. Any move that is attempted that violates the previous is illegal and cannot be played. illegal = Not Legal
illegal en passant? No, a illegal move which happens to be an attempted en passant
If the pawn is pinned to the King, and playing en passant would put the King in check -illegal move.
En passant can only be played when a pawn on its first move is moved two squares - a legal move as long as it does not put that players King in check.
If the pawn only moved one square it cannot be captured en passant because it violates the rule- an illegal move.
Capture by En passant must be done immediately which is a legal move. Trying to capture later is not a legal move.