BMW L7 Back Up Light Bulb Size

The BMW L7 back up light requires a bulb size of P21W for the rear lighting assembly. Data for the specified vehicle covers the range from 1986 to 1987.

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
1986-1987	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 specified back up light bulb for the BMW L7 across the 1986-1987 model years.
The P21W operates on 12 volts with a 21-watt output, placing it in the standard single-filament signalling category.
The P21W uses a BA15s bayonet base, which is a single-contact bayonet fitting with a 15mm collar.
As an ECE-standard bulb, the P21W is governed by European and international regulations, making it widely available across global markets.
The single-filament design of the P21W means it serves one dedicated function, which in this application is the back up light circuit.
The BA15s base designation indicates a non-indexed fitment, distinguishing it from the BA15d dual-contact variant and making the two types non-interchangeable despite their similar physical appearance.