The BMW 428i uses a D1S bulb size for low beam headlights and either D1S or H7 bulb sizes for high beam headlights. The replacement chart covers 2014 to 2016 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 428i uses two distinct bulb types across its headlight system for the 2014-2016 model years: the D1S for HID-equipped vehicles and the H7 for halogen-equipped vehicles.
The D1S is a high-intensity discharge (xenon) bulb rated at 85V and 35W, built to the ECE standard for use in projector-type housings. It 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 wiring system.
The H7 is a single-filament halogen bulb rated at 12V and 55W, using a PX26d base. Unlike the D1S, it holds approval not only under the ECE standard but also in the United States and Japan.
On the BMW 428i, the high beam headlight position accepts either a D1S or an H7 depending on which headlamp system is installed, while the low beam headlight position is fitted exclusively with the D1S across all three model years covered.
The D1S and H7 use different base types, PK32d-2 and PX26d respectively, making them physically incompatible with each other's sockets. A vehicle fitted with HID projector housings cannot accept an H7 in place of a D1S.
Because the D1S includes an integral ignitor, replacing it differs from replacing a conventional halogen bulb. The ignitor is part of the bulb assembly itself, so a replacement D1S unit includes that component by default.
The voltage difference between the two bulb types is substantial. The D1S operates at 85V while the H7 operates at 12V, reflecting the fundamentally different electrical systems that HID and halogen headlamp configurations require.
Both the D1S and H7 conform to ECE regulations, which govern bulb performance and safety standards across Europe and much of the rest of the world outside North America.