BMW Alpina B7 Back Up Light Bulb Size

The BMW Alpina B7 back up light requires a 921 bulb size for proper installation and function. Available information covers the specific time range from 2007 through 2015.

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
2011-2015	921
2007-2008	921

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921

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Additional Notes

The 921 is the sole bulb size listed for the back up light across all model years of the BMW Alpina B7 covered in these specifications.
The 921 bulb follows the ANSI standard, which is the recognized lighting specification framework used in the United States and Canada.
It is a wedge-type bulb, classified under the T15 designation, which refers to its tubular shape and base style that seats directly into a wedge socket without a separate metal base.
The 921 operates at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles.
Its rated wattage is 16W, placing it in the low-power range typical of auxiliary lighting functions such as reverse illumination.
The BMW Alpina B7 years covered in these specifications span 2007-2008 and 2011-2015, all sharing the same 921 bulb fitment for the back up light position.
Because the 921 is a wedge bulb, it is physically interchangeable with other bulbs sharing the T15 wedge base, though wattage and voltage ratings should match the original specification to maintain proper function.