For 2003 and later 325i models with M56 engines, special tools are needed to remove the fuel rail and injectors. Depressurize the fuel system and disconnect the negative battery terminal cable. For M52TU engines, remove the cabin filter cover and housing, and the trim panel. Disconnect the fuel regulator vacuum hose and air intake temperature sensor wiring connector. Remove the fuel rail with the injectors. To remove a fuel injector, pry off the metal securing clip and pull the injector from the fuel rail. For M54 engines, follow the same steps. The fuel pressure regulator on M52TU engines is located within the 
Fuel Tank and cannot be serviced. If defective, the fuel tank must be replaced.