The Mercedes-Benz C55 AMG front fog light requires a 9006 bulb size while the rear fog light uses a P21W bulb size. The replacement chart covers 2005 to 2006 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C55 AMG uses two distinct bulb standards across its fog light positions for the 2005-2006 model years: the ANSI-standard 9006 at the front and the ECE-standard P21W at the rear.
The 9006 is a single-filament halogen bulb rated at 12V and 55W, fitted with a P22d base, and governed by ANSI standards applicable in the United States and Canada.
The P21W is a single-filament signalling bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and governed by ECE standards used in Europe and internationally.
The lower wattage of the P21W relative to the 9006 reflects its role as a signalling bulb rather than an illumination source, as rear fog lights are designed for visibility to following traffic rather than road illumination.
The P22d base of the 9006 and the BA15s bayonet base of the P21W are physically incompatible with each other, meaning the two bulb types are not interchangeable between positions.
The BA15s designation of the P21W base indicates a single-contact bayonet fitting with a 15mm collar, a common format in European automotive signalling applications.
Both fog light positions on the C55 AMG operate on a 12V electrical system, consistent with standard automotive voltage across both bulb types.