Acura ILX Dome Light Bulb Size

Additional Notes

• The Acura ILX dome light specifications reference two distinct bulb types across the 2013-2022 model years: the 12961 and the DE3175, each with a different base design and contact style.
• 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 bulb's glass envelope being gripped directly by the socket contacts, with no separate metal base.
• The DE3175 is an ANSI-standard festoon bulb, recognized in the United States and Canada, with a 31mm length and end-cap contacts. Festoon bulbs make electrical contact through metal caps at each end of the cylindrical body rather than through a wedge or pin base.
• Because the 12961 uses a wedge socket and the DE3175 uses a festoon socket, the two bulb types are not interchangeable. The socket design in the vehicle determines which type is physically compatible.
• The Acura ILX (2017-2022) uses the 12961 bulb for the dome light, while the 2013-2016 model years use the DE3175.
• The 12961's W2.1x9.5d base designation is an IEC standard code describing the wedge contact width and pin spacing, which governs socket fit across manufacturers.
• Both bulb types operate on a 12V electrical system, consistent with standard automotive low-voltage architecture.
• The DE3175 designation combines a festoon-style prefix with the 31mm length value, which is a standard festoon size also referenced in many other vehicle applications, though fitment is still socket-dependent.