The lack of reliability of the diesel locomotive operation leads to a decrease in the technical and economic efficiency of using the locomotive service of the enterprise. During the experiment which aimed at assessing the reliability of repair and maintenance of a diesel locomotive in one of the railway divisions of OJSC “Russian Railways”, it was found that the failures may be distributed by types of equipment, based on the failures for 12 months of 2017. Statistical quality management methods were used to identify the most problematic types of locomotive equipment and specific causes of failures.