Mercedes-Benz GLA45 AMG Back Up Light Bulb Size

The Mercedes-Benz GLA45 AMG back up light requires a 921 bulb size for proper installation and function within the rear lighting assembly. Data for the specified component covers the range from 2015 through 2019.

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
2015-2019	921

Bulb Specifications

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

Other Locations

Additional Notes

The Mercedes-Benz GLA45 AMG uses the 921 bulb for the back up light position across the 2015-2019 model years.
The 921 is a T15 wedge-base bulb, meaning it connects to its socket through a tapered plastic base rather than a bayonet or screw fitting.
The 921 operates at 12 volts and 16 watts, which is consistent with standard automotive low-voltage electrical systems.
The 921 carries ANSI standardization recognized in both the United States and Canada, placing it within a defined performance and fitment classification shared across many vehicle manufacturers.
The T15 designation refers to the bulb's tubular envelope size, with the numeric portion indicating a width of 15 eighths of an inch.
Wedge-base bulbs such as the 921 are not interchangeable with bayonet-base or festoon-style bulbs, as the socket type is physically incompatible.