The Mercedes-Benz ML55 AMG brake light utilizes a P21W bulb size for the specific lighting component located at the rear of the vehicle. Data for the bulb specifications covers the range from 2000 to 2003.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz ML55 AMG uses the P21W bulb across all brake light positions for model years 2000-2003, including both the standard brake lights and the center high mount stop light.
The P21W is an ECE-standardized bulb type, meaning its specifications are governed by the Economic Commission for Europe regulatory framework, which is applied across European and many worldwide automotive markets.
P21W bulbs operate at 12 volts with a 21-watt output, which is a typical rating for single-filament stop and signal applications in passenger vehicles.
The single-filament design of the P21W means it serves one dedicated function per bulb, as opposed to dual-filament types that handle two functions such as running light and brake light within a single unit.
The P21W uses a BA15s bayonet base, where "BA" denotes a bayonet cap fitting, "15" refers to the 15mm base width, and the lowercase "s" indicates a single contact at the base, which corresponds to its single-filament construction.
The BA15s base is not interchangeable with the BA15d base, which carries a dual-contact configuration. Installing a dual-contact bulb in a single-contact socket is not compatible with the ML55 AMG brake light circuit.
Because the same P21W specification applies to both the standard brake lights and the center high mount stop light on the ML55 AMG, a single bulb type covers all three brake light positions on the vehicle.