BMW 430i Gran Coupe high beam and low beam headlight bulbs both utilize the D1S size. The replacement chart covers 2017 to 2018 model year specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The D1S bulb type is specified for both high beam and low beam headlight positions across the 2017-2018 BMW 430i Gran Coupe, applying exclusively to vehicles equipped with HID headlamps.
D1S is a High-Intensity Discharge (HID) xenon bulb, meaning it produces light by passing an electrical arc through xenon gas rather than heating a filament, which is the mechanism used in conventional halogen bulbs.
The D1S bulb operates at 85 volts and 35 watts, a voltage level far above standard automotive electrical systems, requiring a ballast to step up the vehicle's 12-volt supply before the arc can be sustained.
A defining characteristic of the D1S is its integral ignitor, which is built directly into the bulb unit rather than housed separately in the vehicle's wiring system, distinguishing it from the D2S bulb type where the ignitor is external.
The D1S uses a PK32d-2 base, a keyed connector design that physically prevents substitution with other HID bulb types sharing different base configurations, such as the D2S with its PK32d-3 base.
The D1S is rated to the ECE standard, a regulatory framework recognized across Europe and numerous other markets worldwide, governing the bulb's photometric output and safety requirements.
D1S bulbs are designed specifically for projector-type headlight housings, which use a lens and reflector system to focus the arc discharge precisely; substitution into reflector-type housings would produce uncontrolled light scatter.