The BMW 530i brake light utilizes a P21W bulb size for illumination across all listed vehicle applications. Available data for the specified component covers the range from 1975 through 2007.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21W is the sole bulb type listed across all brake light positions for the BMW 530i, covering both the standard brake lights and the Center High Mount Stop Light.
The P21W operates at 12 volts with a 21-watt output, classifying it as a single-filament bulb suited for on/off signalling functions rather than variable-intensity applications.
The P21W uses a BA15s bayonet base, which is a single-contact bayonet fitting. The "s" designation indicates a single offset pin, distinguishing it from the dual-contact BA15d variant.
The P21W is governed by ECE (Economic Commission for Europe) standards, meaning it is a globally recognized specification used across European and international vehicle markets.
The single-filament construction of the P21W means it is dedicated solely to brake signalling and is not a dual-function bulb sharing a filament with a tail light circuit.
For the BMW 530i, the standard brake light position uses the P21W across model years spanning 1975-1978 and 2001-2007.
The Center High Mount Stop Light on the BMW 530i also uses the P21W, with fitment recorded for model years 1994-1995 and 2001-2003.
Because both the standard brake light and the Center High Mount Stop Light share the P21W specification, the same bulb type serves multiple brake-related positions on the vehicle.
The BA15s base is not interchangeable with the BA15d base despite sharing the same 15mm collar size, as the pin configuration differs between the two.