BMW 330i Dome Light Bulb Size

The BMW 330i Dome Light utilizes 12961 and DE3423 bulb sizes according to the provided specifications for various vehicle versions. Data for the specific lighting components covers a range from 2001 through 2018.

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
2017-2018	12961
2004-2006	DE3423
2002-2003	12961
2001	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 330i dome light specifications reference two distinct bulb types across the listed model years: the 12961 and the DE3423.
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 T10 wedge base design uses a plastic wedge-shaped base with embedded wire contacts rather than a separate metal socket, which is a common format in low-current automotive interior applications.
The DE3423 is an ANSI-standard designation recognized in the United States and Canada, referring to a festoon-style bulb with a 41mm length and end-cap contacts, rated at 12V.
Festoon bulbs make electrical contact through metal caps at each end of the cylindrical body, a configuration suited to spring-loaded dome light housings.
The two bulb types are not interchangeable, as the T10 wedge base and the 41mm festoon end-cap format are physically and electrically incompatible with each other's housings.
The BMW 330i (2017-2018) uses the 12961 T10 wedge bulb for the dome light.
The 2004-2006 model years share the DE3423 festoon bulb, while the 2001 model year also uses the DE3423, making it the specified type for four of the eight listed years.
The 2002-2003 model years use the 12961 wedge bulb, the same type specified for the 2017-2018 years.
The dome light bulb type for the BMW 330i is not consistent across all listed model years, with the specified bulb alternating between the wedge and festoon formats at different points in the production timeline.