Scion xB Trunk Bulb Size

Additional Notes

• The DE3423 festoon bulb is the most frequently specified trunk bulb across the Scion xB range, covering the 2008-2014 model years as well as the portion of the 2015 model year produced before April 2015.
• Festoon bulbs make contact with the socket through metal end-caps at both ends of the bulb body rather than through a base pin or wedge, which is the defining characteristic of the festoon form factor.
• The DE3423 and DE3175 are both ANSI-standardized designations recognized in the United States and Canada, operating at 12V and sharing the same festoon contact style, but they are not interchangeable due to a difference in body length: the DE3423 measures 41mm while the DE3175 measures 31mm.
• The Scion xB (2004-2006) uses the shorter DE3175 festoon bulb in the trunk, and installing the longer DE3423 in its place would result in a fitment mismatch.
• From April 2015 onward, the xB transitioned to the 12961, a T10 miniature wedge bulb rated at 12V and 5W with a W2.1x9.5d base, representing a different bulb form factor entirely from the festoon types used in earlier model years.
• The W2.1x9.5d base designation describes a wedge-style base with a 2.1mm wire contact width and a 9.5mm insertion depth, which is a standardized international base code used across multiple manufacturers.
• The 12961 is a Philips part number rather than an ANSI or cross-industry standard designation, meaning equivalent bulbs from other manufacturers would be referenced by different part numbers despite sharing the same T10 form factor and electrical ratings.
• The 2015 model year of the Scion xB carries two distinct trunk bulb specifications depending on production date, with the DE3423 applying to units produced through April 2015 and the 12961 applying to units produced from that point forward.