Mercedes-Benz 600SEL Back Up Light Bulb Size

The Mercedes-Benz 600SEL back up light requires a P21W bulb size for the specific lighting component. Data for the bulb specifications covers the range from 1992 to 1993.

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
1992-1993	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 P21W is the specified back up light bulb for the Mercedes-Benz 600SEL across the 1992-1993 model years.
The P21W is an ECE-standard single-filament bulb rated at 12 volts and 21 watts, mounted on a BA15s bayonet base.
The BA15s designation refers to a single-contact bayonet base with a 15mm collar, which is not interchangeable with the BA15d double-contact variant despite sharing the same physical collar size.
As a single-filament bulb, the P21W serves dedicated switching functions such as reverse lighting, where only one circuit state is required rather than variable intensity.
The ECE designation indicates the P21W conforms to United Nations Economic Commission for Europe regulations, a standard adopted across European and numerous worldwide markets.
At 21 watts, the P21W sits in the upper range of common single-filament signal bulbs, producing a relatively high light output suited to the functional visibility demands of a reverse lamp.