Mercedes-Benz 280S Back Up Light Bulb Size

The Mercedes-Benz 280S back up light utilizes a P21W bulb size for illumination purposes. Available data for the specified component covers the period from 1968 through 1976.

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
1975-1976	P21W
1968-1971	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 280S uses the P21W bulb across all listed model years for its back up light application.
The P21W is an ECE-standard bulb, meaning it conforms to the United Nations Economic Commission for Europe regulations, which govern automotive lighting across European and many worldwide markets.
This bulb operates on a 12-volt electrical system and draws 21 watts, which is typical for single-filament signalling applications such as reverse lights.
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 BA15s base carries only a single contact, the P21W is not interchangeable with visually similar bulbs that use a BA15d (dual-contact) base, even though the physical housing may appear nearly identical.
The single-filament construction of the P21W means it serves one lighting function only, distinguishing it from dual-filament bulbs that combine two functions, such as stop and tail, within one unit.
The 280S used the P21W for back up lights across the 1968-1971 model years and again for 1975-1976, with no variation in bulb specification across those years.