  In this paper we prove that under certain conditions in a quasi Einstein semi
Riemannian warped product the fiber is necessarily a Einstein manifold. We
provide all the quasi Einstein manifolds when r Bakry Emery tensor is null, the
base is conformal to an n-dimensional pseudo-Euclidean space invariant under
the action of an n - 1 dimensional translation group and the fiber is Ricci
flat. As an application, we have built a family of Ricci flat Einstein warped
product whose base is not locally conformally flat.
