a b s t r a c tLet K be a field of characteristic zero, n ≥ 1 an integer and A n+1 = ⟩ the (n+1)th Weyl algebra over K . Let S ∈ A n+1 be an order-1 differential operator of the typeWe construct an algorithm that allows one to recognize whether S generates a maximal left ideal of A n+1 , hence also whether A n+1 /A n+1 S is an irreducible non-holonomic A n+1 -module. The algorithm, which is a powerful instrument for producing concrete examples of cyclic maximal left ideals of A n , is easy to implement and quite useful; we use it to solve several open questions.The algorithm also allows one to recognize whether certain families of algebraic differential equations have a solution in K [X, Y 1 , . . . , Y n ] and, when they have one, to compute it.