Vocational high schools, receive special attention from the government to produce graduates who are skilled and in line with the demands of the 21st century. The COVID-19 pandemic has disrupted the education system, necessitating a shift from offline to online learning methods. This research focuses on developing digital simulator learning (DSL) media to improve the prior or initial knowledge and problem-solving skills of vocational school students in the field of motorcycle engineering and business. The novelty of DSL media is that students not only learn through the reading process but can also see visually through the simulation process, and also simulate troubleshooting on vehicles. This study follows the analysis, design, development, implementation, and evaluation (ADDIE) model. The research results found that smartphone-based DSL media affected increasing competence in initial knowledge of injection systems, while the effectiveness of DSL media was at a medium level.