BMW 330i Map Light Bulb Size

The BMW 330i map light uses 12961 and DE3423 bulb sizes for interior illumination. Available data covers the range from 2001 through 2006 for the specified lighting components.

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
2004-2006	12961
2001-2003	12961 (Front With Dome Light and Rear)
2001-2003	DE3423 (Front Without Dome Light)

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 12961 is a Philips part number designating a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12 volts and 5 watts.
The T10 wedge form factor uses a plastic wedge base that makes direct contact with the socket without a separate metal base, which is a common construction in low-wattage interior lighting applications.
The DE3423 is an ANSI-standardized festoon bulb rated at 12 volts, measuring 41mm in length, and making electrical contact through metal end caps at each end of the bulb body.
The W2.1x9.5d base designation on the 12961 specifies a wedge base where 2.1mm refers to the wire contact width and 9.5mm refers to the base depth, ensuring a defined fit within compatible sockets.
For the BMW 330i model years 2004-2006, a single bulb size, the 12961, is specified across all map light positions without further qualification.
For model years 2001-2003, the BMW 330i uses two distinct bulb types depending on trim configuration: the 12961 for front map lights equipped with a dome light and for rear positions, and the DE3423 for front map lights in vehicles without a dome light.
The 12961 and DE3423 are not interchangeable, as they use fundamentally different base types, a wedge base versus festoon end caps, and are physically incompatible with each other's sockets.
The festoon and wedge base types serve different socket designs, meaning the correct bulb type for the BMW 330i depends on the specific interior configuration of the vehicle rather than the model year alone in the 2001-2003 period.