Mercedes-Benz E550 Back Up Light Bulb Size

The Mercedes-Benz E550 utilizes a back up light with a specific 921 bulb size for the rear illumination system. Data for the lighting components covers the period from 2008 through 2013.

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
2008-2013	921

Bulb Specifications

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

Other Locations

Additional Notes

The Mercedes-Benz E550 uses the 921 bulb size for the back up light across the 2008-2013 model years.
The 921 is a wedge-type bulb, classified under the T15 designation, which refers to its tubular glass envelope size of 15/8 inches.
Wedge bulbs use a pinched glass base as the electrical contact, eliminating the need for a separate metal base or pins found on other bulb types.
The 921 operates at 12 volts and draws 16 watts, which is consistent with standard automotive low-current lighting circuits.
The 921 follows the ANSI standard, meaning it conforms to specifications recognized in both the United States and Canada.
The T15 wedge format is a common platform for back up lights, and the 921 shares its base type with several other bulb numbers in the same family, though wattage and voltage ratings can differ between them.
When replacing the back up light bulb on the E550, the wedge base must seat fully and securely into the socket, as an improper fit can cause intermittent contact or failure.