The maintenance team used a professional cleaning agent to soak and clean the needle valve and valve seat, and polished the contact surface with oxide chromium abrasive paste to restore the flexibility of the needle valve. After reassembly and debugging, the cylinder missing fault was eliminated, and the forklift resumed normal operation. The maintenance experts reminded that the use of qualified diesel fuel is the key to preventing the needle valve sticking of Caterpillar 0R-3002 injectors, and regular cleaning of the injectors can also effectively reduce the occurrence of such faults.