Mercedes-Benz GLK250 Back Up Light Bulb Size

The Mercedes-Benz GLK250 back up light requires a bulb size of 921 for the rear illumination component. Data for the specific bulb requirements covers the range from 2013 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
2013-2015	921

Bulb Specifications

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

Other Locations

Additional Notes

The Mercedes-Benz GLK250 uses the 921 bulb for the back up light across the 2013-2015 model years.
The 921 is a wedge-style bulb, classified under the T15 designation, which refers to its tubular glass envelope size of 15/8 inches in width.
Wedge bulbs use a pinched glass base as the electrical contact point, eliminating the need for a separate metal base or pins.
The 921 operates at 12 volts and draws 16 watts, which is standard for incandescent reverse lighting applications in passenger vehicles.
The 921 follows the ANSI standardization system, meaning its electrical and physical specifications are regulated for consistent performance across compliant products in the United States and Canada.
Because the 921 is an ANSI-standardized wedge bulb, it is interchangeable with other bulbs sharing the same T15 wedge base and 12V/16W rating, provided the physical fit within the socket housing is confirmed.