Honda Insight Dome Light Bulb Size

Additional Notes

• The Honda Insight dome light uses one of two bulb types across its model years: the 12961 and the DE3175, each with a distinct base design that makes them physically incompatible with each other.
• 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 the glass envelope itself being gripped by the socket contacts rather than a separate metal base.
• The DE3175 is an ANSI-standard festoon bulb recognized across the United States and Canada. It measures 31mm in length and makes electrical contact through metal end caps at both tips of the cylindrical body, a fundamentally different mounting method from the wedge design of the 12961.
• The Honda Insight (2000-2006) uses the 12961 bulb for the dome light, as does the 2021-2022 model year range.
• The DE3175 fitment applies to the Honda Insight for model years 2010-2014 and 2019-2020, covering both the second and third generations of the vehicle.
• Because the 12961 and DE3175 use entirely different base types, one cannot substitute for the other regardless of voltage compatibility. Socket design is the determining factor in fitment.
• The DE3175 designation does not carry a wattage specification in these listings, whereas the 12961 is explicitly rated at 5W. Both operate on a 12V automotive electrical system.
• The 31mm length of the DE3175 is a critical fitment attribute for festoon bulbs, as festoon sockets are sized to hold a specific bulb length under spring tension from the end-cap contacts.