11377599021 11377603979 Cylinder Head Valvetronic Timing Actuator Motor for N20 N55 135i 228i 320i 328i 428i This actuator mounts on the valve cover and controls the position of the intermediate shaft in the Valvetronic variable valve lift system.It is designed for the third generation of the Valvetronic system, combining the functions of actuator and which were previously separate components.The unit is constructed with metal materials and features mechanical stability and corrosion resistance.Compatible with vehicles equipped with N20 and N55 engines including models such as 135i, 228i, 320i, 328i, 428i, and other applicable variants from 2010 to 2016.Fits engine types N20B20A and N55B30A.Package includes one Eccentric Shaft Motor.This unit has been refurbished and tested for functionality.Installation requires removal of the valve cover, ignition coils, and fuel injectors.The two injector housings adjacent to the motor must be removed, followed by the mounting bolt and bracket.Carefully rotate the gear to disengage the minimum stopper and create space for removal.Gently slide out the old motor and install the replacement.Common symptoms of a faulty Valvetronic actuator include illuminated check engine light, power loss, rough idle, increased fuel consumption, hard starting or no start condition.Mechanical noises may or may not be present even if there is a fault.