By opening up a technology, firms can incorporate external actors to improve their products or to develop new applications on top of it. This phenomenon is discussed in the literature as open innovation (Chesbrough, 2003). An embedded system is an example of a modular and traditionally closed technology where parts of the system can be opened in order to stimulate innovation. In this paper, we want to explore how firms can pursue the opening of their embedded systems and their organization in order to unleash the potential of open innovation. By conducting twelve explorative interviews with experts in the field of embedded systems, we discovered three different forms of embedded systems openness and explored technical, internal and external organizational challenges associated with these three forms of openness.