Mercedes-Benz GLA250 Back Up Light Bulb Size

The Mercedes-Benz GLA250 back up light utilizes a 921 bulb size for the specific lighting component located at the rear of the vehicle. Data for the bulb size covers the range from 2015 through 2023.

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
2015-2023	921

Bulb Specifications

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

Other Locations

Additional Notes

The Mercedes-Benz GLA250 uses the 921 bulb for the back up light across the 2015-2023 model years.
The 921 is a T15 wedge-base bulb, meaning it connects via a plastic wedge-shaped base rather than a bayonet or screw fitting.
The 921 operates at 12 volts and 16 watts, which places it in the low-wattage range typical of reverse lighting applications.
The 921 conforms to ANSI standards, indicating it meets a defined specification recognized across the United States and Canada for consistent electrical and physical characteristics.
The T15 designation refers to the bulb's tubular envelope, with the numeric portion indicating a width of 15 eighths of an inch.
The wedge base design of the 921 is not interchangeable with bayonet-style or screw-base sockets, as the retention and contact method differs fundamentally between these base types.