Model Driven Engineering (MDE) promotes models as main artifacts in software development process. Each model represents a viewpoint of a system. MDE aims to automatically generate code from an abstract model, using various intermediary models. Such a generation relies on successive model transformations shifting a source model to a target one. The resulting transformation sequence corresponds to the skeleton of an MDE based approach, similarly to compiler in traditional ones. Transformations are used many times in order to justify their development effort. If their are faulty, they can largely spread errors to models. Thus, it is indispensable to test them and possibly debug them. In this paper, we propose an error localization algorithm based on a traceability mechanism in order to ease the transformations debugging. We illustrate this approach in the context of embedded system development.