The BMW 440i uses D1S bulb size for both high beam and low beam headlight applications. The replacement chart covers 2017 to 2018 model years with corresponding bulb size 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 a High Intensity Discharge (HID) xenon bulb operating at 85 volts and 35 watts, distinguishing it from conventional halogen bulbs that operate at 12 volts.
The D1S bulb features a PK32d-2 base with an integral ignitor, meaning the ignitor is built directly into the bulb unit rather than housed separately in the vehicle's electrical system.
D1S bulbs are designed exclusively for projector-type headlamp housings, making them incompatible with reflector-type housings without modification.
The D1S designation follows the ECE (Economic Commission for Europe) standard, which governs bulb specifications across Europe and numerous other markets worldwide.
The BMW 440i uses the D1S bulb for both high beam and low beam headlight positions in 2017-2018, with the HID headlamp configuration applying to both functions.
Because the D1S bulb carries an integral ignitor, substituting it with a D1R bulb, which shares the same base and wattage, is not recommended; the two types differ in their beam-shielding design and are not interchangeable despite physical similarities.