FD1 - Fuel Injector Function

^ With the engine warmed and idling (or cranking if it does not start) and using a mechanic's stethoscope or equivalent, listen for regularly operating sounds at each fuel injector.

^ Is operating sound present?

YES -- Go to FD4. [1][2]FD4 - Fuel Injector Cleaning and Leakage Check

NO -- Go to FD2. FD2 - Fuel Injector Electrical Signal