Mercedes-Benz S500 Back Up Light Bulb Size

The Mercedes-Benz S500 back up light utilizes a P21W bulb size for illumination purposes. Available data covers the span from 1994 through 2006 for the specified vehicle component.

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
1994-2006	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 S500 uses the P21W bulb for the back up light position across all listed model years, spanning 1994-2006.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework used in European and worldwide automotive lighting applications.
P21W bulbs operate on a 12-volt electrical system and draw 21 watts, which is typical for single-filament incandescent signalling applications.
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.
Because the P21W is a single-filament bulb, it serves one lighting function only, which in this case is the back up light.
The BA15s base is not interchangeable with the BA15d base, which carries two contacts for dual-filament bulbs. Substituting a BA15d bulb in a BA15s socket is not compatible.
The consistent P21W fitment across the full 1994-2006 model year range of the S500 reflects a stable lighting specification held throughout that generation and its successor within the listed data.