Mercedes-Benz S430 Back Up Light Bulb Size

The Mercedes-Benz S430 back up light utilizes a P21W bulb size for illumination purposes within the rear housing assembly. Data for the specific component 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.

Bulb Size by Year Range

Years	Bulb Size
2000-2006	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The Mercedes-Benz S430 uses the P21W bulb as the back up light bulb size across all listed model years from 2000-2006.
The P21W is an ECE-standardized bulb type, meaning it conforms to regulations used in Europe and internationally rather than SAE standards common in North American automotive applications.
The P21W operates at 12 volts with a 21-watt output, which is a relatively high wattage for a single-filament signal bulb and reflects its use in high-visibility applications such as reverse lighting.
The P21W uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm base width, distinguishing it from dual-contact variants such as the BA15d.
Because the P21W is single-filament, it serves one dedicated function per housing, unlike dual-filament bulbs that can serve two functions from a single unit.
The BA15s base type is not universally interchangeable with other 15mm bayonet bases; the dual-contact BA15d, for instance, shares a similar physical profile but has a different electrical configuration, making substitution between the two unsuitable.