N75 (automotive)

An electronic solenoid valve that controls VNT turbochargers in TDi. ECU controls N75 valve opening, which results in increase or decrease of boost. N75 usually controls either actuator via vacuum system or boost loop directly connected to turbocharger housing. N75 has been replaced by servo controlled actuators mounted on turbocharger, which replaces complicated design of extra vacuum system such as vacuum pump, hoses that weather and tend to leak or rusty mechanical actuator.