The Mercedes-Benz ML500 brake light utilizes a P21W bulb size for illumination during vehicle operation. Data for the specified component covers the range from 2002 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 specified across all brake light positions on the Mercedes-Benz ML500, covering both the standard brake lights and the Center High Mount Stop Light for model years 2002-2007.
The P21W operates at 12 volts with a 21-watt output, classifying it as a single-filament bulb suited exclusively for signalling functions rather than continuous illumination.
The single-filament design of the P21W means it produces one fixed level of light output, with no capacity for a dimmed running light mode alongside a brighter stop signal.
The P21W uses a BA15s bayonet base, which is a single-contact bayonet fitting with a 15mm collar. The "s" designation indicates a single contact pin, distinguishing it from the dual-contact BA15d variant.
The P21W is governed by ECE regulations, a standards framework used across Europe and numerous other markets worldwide, which defines its electrical and photometric performance requirements.
Because the BA15s and BA15d bases share the same collar size, a dual-contact BA15d bulb can physically seat in a BA15s socket, though the electrical circuits differ. Substituting one for the other risks incorrect brake light function on the ML500.
The consistent use of P21W across both the standard brake lights and the Center High Mount Stop Light on the Mercedes-Benz ML500 means a single bulb specification covers all three brake light positions throughout the 2002-2007 model range.