This article describes a case study applied in a commercial vehicle company, with a focus on analyzing and reducing process failures generated in the products' pneumatic brake system. The production method of the assembly line based on the concept of flexible sequencing, with alternation of models, which makes the assembly of the brake system complex, contributing to a potential scenario of failures such as leaks and loss of efficiency of the brake system. The methodology used based on the DMAIC method (Define, Measure, Analyze, Improve, Control) for failure analysis, together with Quality Tools, such as Brainstorming, Ishikawa, and Pareto Diagram. The results of the evaluations made it possible to identify the causes that had a strong relationship with the failure mode pointed out in the Process FMEA, generating an Action Plan for pneumatic leaks, thus achieving a significant reduction in the company's quality indicator, proving the importance and necessity of using failure analysis methods.