The maintenance technicians checked the power supply and wiring of the 0R-3002 injectors and found that they were normal. After disassembling the injectors, it was found that the internal circuit of the injectors was faulty, the solenoid valve coil was open-circuited, and the circuit board was damaged. The reason for the circuit failure was that the injectors were affected by voltage fluctuation during operation, leading to damage to the internal circuit. In addition, the injectors had been used for a long time, and the internal components were aging.