Introduction: Most studies on terminal diagnostics of dynamic systems are devoted to the description of methods of calculatingspecial test signals providing natural movement of the system, for example, within the given limits. Such a movement is carried outusing calculated terminal control. The final state of the system allows you to determine a diagnostic feature. Therefore, it is necessaryto set and solve the problem of assessing the probability of obtaining a correct result of diagnosis, which would determine its reliabilityand sensitivity to errors in the system movement caused by a defect. Purpose: Developing methods for calculating the reliability andsensitivity of a diagnostic feature in terminal diagnosis of dynamic systems. Methods: Formulas based on the theory of automaticcontrol system sensitivity allowed us to obtain conditions for detecting defects which lead to errors in the system movement withinspecified boundaries. Results: Methods have been developed to calculate dynamic system motion error sensitivity coefficients forvarious defects and required initial data. The process of evaluating terminal diagnostics of discrete dynamic systems is described. Thisprocess differs from the known methods in that the test motion is a natural movement of the system within the specified boundaries.Computer simulation confirms that the obtained formulas of the diagnostics process estimation are accurate. The proposed formulasrequire the application of MATLAB mathematical package, as the calculation is based on function programs and a scenario for studyingreliability and sensitivity of terminal diagnostics.Practical relevance: When making a decision about the presence of a defect in a testeddynamic object, the technical diagnostics system operator receives a tool for assessing the reliability and sensitivity of the diagnosticfeature.