Signs of a malfunction of a diesel engine include increased emission of smoke accompanying engine operation, engine starting problems, noises during engine operation, and unstable engine operation with a decrease in power. During diagnostics, an expert will check the readings of temperature sensors, readings of a mass air flow sensor, values of vacuum converters, value of compression in the cylinders of the unit, will assess the state of the combustion chamber and cylinders, will detect the cylinder leaks and will take other measures. The engine is a complex unit. Therefore, all methods are used for verification, from visual inspection and acoustic assessment to computer diagnostics.