Mercedes-Benz E350 Trunk Bulb Size

The Mercedes-Benz E350 trunk light uses 12961 and DE3423 bulb sizes for the lighting components located inside the rear cargo area. Provided information covers the specific time span from 2006 through 2023 for the listed vehicle and lighting equipment.

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
2020-2023	12961
2008-2016	12961
2006-2007	DE3423

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V.	DE3423

Other Locations

Additional Notes

The Mercedes-Benz E350 trunk uses two distinct bulb types across its model years: the 12961, a miniature wedge bulb, and the DE3423, a festoon bulb. These two types are not interchangeable due to their fundamentally different base designs.
The 12961 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W. The wedge base relies on wire contacts pressed against the sides of the bulb's glass pinch, requiring no separate socket pins.
The DE3423 is an ANSI-standard festoon bulb, 41mm in length, with end-cap contacts at each end. It operates at 12V and makes contact through metal caps rather than a wedge or pin base, making it physically incompatible with sockets designed for the T10 wedge format.
The 2006-2007 E350 uses the DE3423 festoon bulb for the trunk. Substituting a T10 wedge bulb in a festoon socket would result in improper fitment, as the socket geometry does not accommodate a wedge-style base.
The 12961 T10 wedge bulb is specified for the 2008-2016 and 2020-2023 E350 trunk positions. The W2.1x9.5d base designation refers to a standardized wedge contact width of 2.1mm with a 9.5mm pin spacing equivalent, ensuring consistent fitment across compatible sockets.
The 5W power rating of the 12961 places it in the low-wattage category typical of interior and cargo area lighting, where heat output and current draw are kept minimal.