Diagnostics of the electronic control unit (ECU) is carried out in the following cases: there are no control signals coming from control mechanisms, for example, injectors, ignition system, idle speed regulator, fuel pump; there is no response to lambda adjustment or temperature sensors; it is impossible to carry out automatic diagnostics. After a visual inspection, diagnostic equipment is connected to the control system, the control unit is scanned, and error codes are read. Next, an expert checks the power supply, startup and synchronization of the ECU.