Mercedes-Benz 300SL Back Up Light Bulb Size

The Mercedes-Benz 300SL back up light requires a P21W bulb size for proper installation and function. Data for the specified lighting component covers the range from 1990 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
1990-1993	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 Mercedes-Benz 300SL uses the P21W bulb for its back up light across the 1990-1993 model years.
The P21W is an ECE-standardized bulb, meaning it conforms to European and international regulations for automotive lighting.
P21W bulbs operate on a 12-volt electrical system and draw 21 watts, which is typical for single-filament signalling applications.
The P21W uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin offset to one side of the base.
Because the BA15s base is a single-contact design, it is not interchangeable with the BA15d base, which carries two contacts for dual-filament bulbs.