The Mercedes-Benz ML63 AMG tail light requires a P21W or P21/4W bulb size depending on the specific configuration of the lighting assembly. Data for the lighting components covers the range from 2007 to 2011.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21W is a single-filament signalling bulb operating at 12V and 21W, built to the ECE standard used across Europe and worldwide. It uses a BA15s bayonet base, which is a single-contact fitting.
The P21/4W is a dual-filament signalling bulb also rated at 12V, with two wattage outputs of 21W and 4W. It follows the same ECE standard but uses a BAZ15d bayonet base, which is an offset dual-contact fitting not interchangeable with the BA15s base of the P21W.
Because the BA15s and BAZ15d bases are physically distinct, P21W and P21/4W bulbs are not interchangeable despite sharing the same voltage rating and a common wattage value.
In the Mercedes-Benz ML63 AMG outer tail light, the 2007 model year uses the P21/4W for one of its functions, reflecting a dual-filament requirement at that position.
The same outer tail light position on the 2007 ML63 AMG also uses the P21W for a separate function, meaning both bulb types are specified for that single model year.
For the 2008-2011 ML63 AMG, the outer tail light position is served exclusively by the P21W single-filament bulb, with no dual-filament fitment listed for those years.