BMW 2800 Back Up Light Bulb Size

The BMW 2800 back up light requires a P21W bulb size for the specific lighting component. Data for the requested information covers the range from 1969 to 1971.

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
1969-1971	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 P21W is the sole bulb type listed for the BMW 2800 backup light across the 1969-1971 model years.
The P21W operates on a 12-volt electrical system and draws 21 watts, placing it in the single-filament category of automotive signal bulbs.
A BA15s bayonet base is the mounting interface for the P21W. The "s" in BA15s denotes a single-contact base, distinguishing it from the dual-contact BA15d variant, which is not interchangeable.
The P21W is governed by ECE (Economic Commission for Europe) standards, a regulatory framework used across Europe and numerous other markets worldwide.
Because the BA15s base is a single-contact design, substituting a dual-contact bayonet bulb of otherwise similar size would result in an improper fit.