ABSTRACT Worldwide diesel engines will keep their important role for passenger car power trains and especially for commercial engine applications. In Europe the on-road passenger car and truck standard Euro 6 as well as the off-road Stage 4 emission legislation with conventional combustion technology has resulted in significantly more complex after treatment systems. Engine out emission improvement and further fuel economy benefits have always been the driver for innovations in fuel injection systems as a contribution to diesel combustion improvement. Engine test evaluations have now proven the potential of increased injection pressures in combination with multi injection patterns for heavy duty as well as for passenger car engines. Targeting firstly 2500 bar injection pressure and later for commercial applications 3000 bar injection pressure, DENSO developed the fourth generation solenoid injection system. These high rail pressures are achieved by an optimized pump design and a leakage-free solenoid injector. More accurate and flexible multi injection calibration will be enabled by optimized hydraulic design of the injector and via lifetime be further enhanced by i-ART, DENSO’s closed loop injection control using an in-injector pressure sensor.