The BMW 528i brake light uses H21W, P21W, and P21/5W bulb sizes depending on the specific production version. Data for the provided components covers the range from 1979 to 2016.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW 528i brake light specifications cover three distinct bulb types across its model years: the H21W, P21W, and P21/5W, all of which conform to ECE standards used in Europe and worldwide.
The H21W is a single-filament signalling bulb rated at 12V and 21W, distinguished by its BAY9s base. The BMW 528i (2011-2016) uses this bulb in an Adaptive configuration for the brake light position.
The Adaptive designation associated with the H21W indicates the bulb operates within an adaptive braking light system, which typically modulates light output based on braking intensity rather than functioning as a simple on/off signal.
The BAY9s base of the H21W is not interchangeable with the BA15s base of the P21W, despite both bulbs sharing the same 12V/21W electrical rating. Physical base differences prevent direct substitution between these two types.
The P21W is a single-filament signalling bulb rated at 12V and 21W with a BA15s bayonet base. It is specified for the brake light position across the 1997-2010 model years, as well as for the Center High Mount Stop Light on 1997-2000 models.
The P21/5W is a dual-filament signalling bulb with a BAY15d bayonet base, rated at 12V with filaments drawing 21W and 5W respectively. Its BAY15d base features two offset pins that prevent incorrect installation, distinguishing it physically from the single-filament P21W.
The 1980-1981 model years are the only years specified with the P21/5W for the brake light position. The dual-filament nature of this bulb means it serves a combined function, with the lower 5W filament typically used for a secondary purpose such as a tail light.
The 1979 model year uses the P21W rather than the P21/5W used in 1980-1981, indicating a difference in brake light assembly design between these closely adjacent model years.
The Center High Mount Stop Light position is specified only for the 1997-2000 model years, all using the P21W with its BA15s bayonet base.
All three bulb types in these specifications operate on a 12V electrical system, consistent with standard automotive electrical architecture.