BMW X4 high beam and low beam headlight bulbs both utilize the D1S size. The replacement chart covers 2015 through 2018 production 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 BMW X4 (2015-2018) uses the D1S bulb type for both high beam and low beam headlight positions.
The D1S is a High-Intensity Discharge (HID) xenon bulb rated at 85 volts and 35 watts, operating at significantly higher voltage than conventional halogen bulbs.
D1S bulbs incorporate an integral ignitor directly within the bulb unit, meaning the ignitor and bulb are replaced together as a single component rather than separately.
The D1S uses a PK32d-2 base, which is a keyed connector designed to prevent incorrect installation and is not interchangeable with other HID base types such as D2S or D3S.
D1S bulbs are specified for projector-type headlight housings, and substitution with bulbs intended for reflector housings would produce incorrect light distribution.
The D1S designation follows ECE (Economic Commission for Europe) standards, indicating the bulb conforms to internationally recognized photometric and safety regulations used across Europe and other worldwide markets.
The shared D1S fitment across both the high beam and low beam positions in the BMW X4 (2015-2018) indicates the vehicle uses a single projector lens per side that serves dual beam functions through the same bulb.