The BMW 440i Gran Coupe high beam and low beam headlight bulbs both utilize the D1S bulb size. The replacement chart covers vehicle production spanning 2017 to 2018.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The D1S is a High Intensity Discharge (HID) xenon bulb operating at 85 volts and 35 watts, which places it in a significantly higher voltage class than conventional halogen bulbs.
The D1S carries an ECE certification, meaning it meets European and international lighting regulations rather than SAE standards used in North American-specific applications.
A defining characteristic of the D1S is its integral ignitor, which is built directly into the bulb unit rather than housed separately in the ballast circuit, distinguishing it from the D2S which requires an external ignitor.
The D1S uses a PK32d-2 base, a keyed connector design that physically prevents installation of incompatible bulb types into the same socket.
The D1S is specified exclusively for projector-type housings, as its arc geometry and light output are calibrated for that optical system rather than reflector-type housings.
In the BMW 440i Gran Coupe (2017-2018), the D1S bulb serves both the high beam and low beam functions, a configuration made possible by the projector housing's mechanical shutter, which controls beam pattern switching rather than using separate bulbs.
The HID headlamp condition noted in the specifications indicates that D1S fitment applies only to vehicles equipped with the HID headlamp option, meaning not all 2017-2018 440i Gran Coupe units necessarily share this bulb specification.