PurposeThe rising need to innovate and obtain knowledge from more distant knowledge sources calls for new innovation strategies and a better integration of other external actors who lie outside the traditional automotive supply chain. Such an open innovation strategy challenges organizational boundaries both on the firm and supply chain level, yet our understanding of the functioning of such boundaries and how they can be managed to allow for purposive knowledge flows is limited. The paper aims to discuss these issues.Design/methodology/approachIn a longitudinal case study, the authors trace the development of the first open innovation network in the German automotive industry over a period of five years based on archival data, semi-structured interviews, and field observations.FindingsWhile the automotive industry is advanced in collaborating with suppliers for innovation, routines for assessing and integrating ideas from sources outside the supply chain are still underdeveloped. The authors show which current knowledge boundaries pose obstacles for open innovation initiatives in this industry, and how they could be mediated through the involvement of gatekeepers.Originality/valueThe authors challenge and clarify the notion of the “permeability of organizational boundaries” in the open innovation literature and investigate the role of gatekeepers for open innovation.