The BMW M6 brake light requires a P21W bulb size for proper installation and function within the lighting assembly. Data for the specified component covers the range from 1987 through 2010.
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 brake bulb type listed across all BMW M6 model years in the specifications, covering both the standard brake light and the Center High Mount Stop Light positions.
The P21W follows the ECE (Economic Commission for Europe) standard, a regulatory framework governing lighting equipment used in Europe and numerous other markets worldwide.
As a single-filament bulb, the P21W is dedicated to one lighting function, which in this context is braking signalling rather than a combined stop and tail operation.
The P21W operates at 12 volts and 21 watts, the latter figure being a relatively high wattage for a signal bulb, producing a bright, clearly visible output suited to brake light applications.
The BA15s designation refers to a single-contact bayonet base with a 15mm collar, distinguishing it from the BA15d double-contact variant and making the two types non-interchangeable despite their similar physical form.
For the BMW M6, the P21W fitment applies to the 2008-2010 model years for the standard brake light position.
The Center High Mount Stop Light on the BMW M6 carries the same P21W specification, confirmed for the 1987-1988 model years.
The shared P21W specification across both the standard brake light and the Center High Mount Stop Light positions means a single bulb type serves multiple lamp housings on the 1987-1988 M6.