Mercedes-Benz 600 Back Up Light Bulb Size

The Mercedes-Benz 600 back up light utilizes a P21W bulb size for illumination. Available data covers the span from 1964 through 1972 for the specified lighting 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
1964-1972	P21W

Bulb Specifications

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

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Additional Notes

The Mercedes-Benz 600 uses the P21W bulb for its back up lights across all model years listed in the specifications, spanning 1964-1972.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe's regulations, which govern lighting equipment used in Europe and numerous other markets worldwide.
This bulb operates on a 12-volt electrical system and draws 21 watts, which is typical for single-filament incandescent signalling applications.
The P21W carries 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 rather than a dual-contact arrangement.
Because the P21W is a single-filament bulb, it serves one lighting function only, which in this application is the back up light.
The BA15s base is not interchangeable with the BA15d base, as the latter features two offset contact pins and is designed for dual-filament bulbs. Substituting one for the other is not possible without a socket modification.
The nine-year consistency of the P21W fitment across the 1964-1972 Mercedes-Benz 600 indicates a stable electrical and socket specification throughout the production run covered by these records.