Faults and malfunctions occurring in engineering systems may cause additional resources consumptions and economic expenditures, thus their detection and isolation is of great practical significance. The procedure to discover faults is known as diagnosis, and it can be based on different techniques, depending on the purpose of the analysis: to predict the failure time of the component, or to quantify the inefficiencies of the system due to the anomaly. Among the existing approaches adopted to diagnose the energy systems, Thermoeconomic diagnosis provides useful information to detect the anomalies and to quantify its negative impacts. However, this method does not allow to identify possible strategies useful to reduce the inefficiencies caused by anomalies, which could be a crucial need for the system operator. To face this issue, this article proposes a method to perform Thermoeconomic diagnosis of energy systems that enables the analyst to understand the interdependencies between the components, and decomposing the main indicator resulting from Thermoeconomic diagnosis, known as malfunction. The method provides useful information for the system operators to define practical strategies to reduce the negative effects of malfunctions. This approach is also formalized and applied to the CGAM benchmark to highlight the practical achievements of this approach with numerical values. It is found that the proposed approach provides useful insight about the effects of malfunctions, and it may be helpful for system operators to reduce the negative impacts of the anomaly by pinpointing the component with higher contribution in total inefficiency of the system. In this specific case, proper intervention on the pinpointed component mitigated the total inefficiency of the system by almost 40%, and recovered the reference efficiency of the system.