BMW 550i GT Back Up Light Bulb Size

The BMW 550i GT back up light utilizes bulb size 12177 or 921 depending on the specific version of the component. Data for the bulb sizes covers the range from 2010 to 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
2012-2015	12177
2010-2011	921

Bulb Specifications

Description	Bulb Size
Philips part number. Halogen bulb, specialty application. 12V.	12177
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921

Other Locations

Additional Notes

The BMW 550i GT back up light specifications reference two distinct bulb types across the 2010-2015 model years: the 921 and the 12177.
The 921 is an ANSI-standardized wedge-style bulb, classified under the T15 form factor, operating at 12 volts with a 16-watt output. Its standardization under ANSI means it follows a shared specification recognized across the US and Canadian markets.
The 12177 is a Philips part number designation rather than an ANSI industry code, indicating it is a manufacturer-specific halogen bulb intended for specialty applications. It operates at 12 volts.
The 550i GT (2010-2011) takes the 921 bulb for the back up light position.
The 550i GT (2012-2015) takes the 12177 bulb for the same position.
Because the 12177 carries a Philips-specific designation rather than a universal ANSI code, substitution with generic or cross-referenced alternatives warrants attention to ensure the replacement meets the original halogen and voltage specifications.
The 921 and 12177 are not interchangeable. The 921 follows a wedge T15 form factor, while the 12177 is a specialty halogen type, meaning physical fitment and electrical characteristics differ between the two.