Fuel injector failure Fuel line common rail leak Fuel pressure sensor malfunction Fuel pump or lift pump failure Fuel heater constantly on Fuel temperature sensor failure Leaks at any point in the high pressure circuit Electrical connector corrosion or seating problems Fuel pressure regulator malfunction Fuel filter plugged dropping the fuel line volume Injector pump leak Fuel control actuator failure Cascade overflow valve malfunction Short in the electrical harness at the injectors or to the ECM Fuel pressure limiting valve ECM failure