The Fiat 500X dome light utilizes bulb sizes 12961 and DE3423 for interior illumination across various trim levels. Data for the specified components covers the period from 2016 through 2023.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Fiat 500X dome light specifications cover the 2016-2018 and 2021-2023 model years, with two distinct bulb types used across those periods.
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 design means the bulb is held in place by tension from the socket rather than by a separate locking mechanism.
The DE3423 is an ANSI-standardized festoon bulb used in the United States and Canada, measuring 41mm in length and making contact through metal end caps at both terminals, rated at 12V.
The 2021-2023 Fiat 500X uses the 12961 bulb for the dome light, and this same bulb type is also specified for the front dome light position in those same years.
The 2016-2018 Fiat 500X uses the DE3423 festoon bulb for the dome light. The festoon and wedge base types are physically and electrically incompatible with each other, as they rely on entirely different socket designs.
Because the 12961 wedge bulb and the DE3423 festoon bulb use different base configurations, parts from the 2016-2018 specification are not interchangeable with those from the 2021-2023 specification.