Proton exchange membrane fuel cells are promising energy conversion solutions for both stationary and transportation applications. However, for the latter application, durability still needs to be improved in order to compete with internal combustion engine. Therefore, many researches have been carried out to improve their design, materials, reliability and energy management. A good understanding of the degradation mechanisms is one of the keys to a better durability. However, these degradation mechanisms are not yet fully understood. The purpose of this paper is to present a long term durability test performed on a commercial 1 kW open-cathode proton exchange membrane fuel cell system during more than 5000 h under specific operating conditions that aim at reproducing driving cycles, including electrical solicitations, idle, start-up, shutdown, and environmental temperature conditions. This study presents voltage, efficiency and electrochemical impedance spectroscopy measurements evolution all along the system operating duration. Results are used to investigate and understand effects of ambient temperature on the PEMFC system performance and degradation. Analyses could be used in further studies to improve energy management and extend the system durability.