Mercedes-Benz 380SE Back Up Light Bulb Size

The Mercedes-Benz 380SE back up light bulb operates with a P21W size specification. The replacement chart covers 1984 to 1985 vehicle production years and contains bulb size specifications.

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
1984-1985	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 380SE across the 1984-1985 model years.
The P21W follows the ECE (Economic Commission for Europe) standard, a regulatory framework adopted across 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 signalling applications.
The P21W uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin offset, distinguishing it from dual-contact bayonet variants.
Because the BA15s base is a single-contact design, it is not interchangeable with BA15d (dual-contact) bulbs, even though the physical base size appears similar.