BMW 745Li Dome Light Bulb Size

The BMW 745Li dome light utilizes 12961 and DE3423 bulb sizes for the interior lighting system. Data for the specific components covers the range from 2002 through 2005.

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
2003-2005	12961
2002	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

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Additional Notes

The BMW 745Li uses two distinct bulb types across its model years, with the 2003-2005 models specifying the 12961 and the 2002 model specifying the DE3423.
The 12961 is a Philips part number designation for a T10 miniature wedge bulb, which uses a W2.1x9.5d base, operates at 12 volts, and draws 5 watts.
The T10 wedge base design means the bulb is held in its socket by friction through two angled metal contacts on the base, rather than by a locking twist or end-cap pins.
The DE3423 is an ANSI-standardized festoon bulb, recognized across the United States and Canada, with a 41mm length and end-cap contacts at each end of the bulb body.
Festoon bulbs make electrical contact through metal caps pressed against spring-loaded socket contacts, a mounting method that is physically incompatible with wedge-style sockets.
Because the 12961 wedge and the DE3423 festoon use fundamentally different base types, the two bulbs are not interchangeable, and the 2002 745Li dome light socket is not compatible with the bulb specified for the 2003-2005 models.
The 12961 carries a wattage rating of 5W, while the DE3423 specification provided does not include a wattage value, meaning power draw for the 2002 fitment is not established by these specifications.
Both bulb types share a 12-volt operating voltage, consistent with standard automotive electrical systems.