The Mercedes-Benz S430 tail light utilizes a P21/4W bulb size for the lighting components located at the rear of the vehicle. Data for the specified bulb covers the range from 2000 to 2006.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz S430 uses the P21/4W bulb for the outer tail light across all model years covered by these specifications, spanning 2000-2006.
The P21/4W is an ECE-standard bulb recognized across European and worldwide markets, making it a globally regulated type rather than a region-specific component.
P21/4W is a dual-filament bulb, meaning it contains two separate filaments within a single housing, each serving a distinct lighting function at different wattages.
The bulb operates on a 12-volt electrical system, which is standard for passenger vehicles in this class.
The two filaments are rated at 21 watts and 4 watts respectively, with the higher-wattage filament typically associated with braking or turn signal functions and the lower-wattage filament associated with running light functions.
The P21/4W uses a BAZ15d bayonet base, which is an offset twin-contact base design. The offset pin placement is intentional, as it prevents the bulb from being inserted in the wrong orientation, ensuring each filament connects to its correct circuit.
Because the BAZ15d base is orientation-specific, it is not interchangeable with other 15mm bayonet bases such as the BA15d or BA15s, even though the physical size of the base may appear similar.