The occurrence of deposits in the combustion chamber greatly affects engine performance and can affect engine emissions. This will continue to happen when using fuels derived from fossil fuels. To determine the occurrence of these deposits, research is carried out to determine the process of deposit formation, composition and structure as well as other influences that can cause deposits to occur to overcome deposits in the engine room. The purpose of this study was to determine the structure, morphology of Biodiesel B30 deposit Fatty Acid Methyl Esters (FAME), and Hydrotreated B30 from deposition test rigs using Scanning Electron Microscopy (SEM) and EDX (Energy Dispersive X-Ray) methods. Based on this test, the carbon element in the Biodiesel B30 FAME deposit is higher than that of hydrotreated fuel. Other components are also found in B30 FAME such as Oxygen, Nitrogen and also found in metal elements, which in Hydrotreated only a little