Jaguar XK front and rear side marker bulbs utilize a 12961 bulb size for replacement applications. The replacement chart covers vehicle production spanning 2007 to 2015.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 12961 is a Philips-designated miniature wedge bulb operating at 12 volts and 5 watts, built on the T10 form factor with a W2.1x9.5d base.
The W2.1x9.5d base is a wedge-type connection, meaning the bulb is held in place by tension from the socket rather than by a bayonet or screw mechanism.
The Jaguar XK uses the 12961 bulb across all listed front side marker positions for the 2010-2015 model years.
The rear side marker positions for the 2007-2009 Jaguar XK also specify the 12961 bulb, making it the sole bulb type referenced across all side marker positions in these specifications.
The T10 designation refers to a bulb body that is approximately 10mm wide, a standard sizing classification within the miniature wedge bulb family.
At 5 watts, the 12961 operates at a low power draw consistent with side marker and parking light applications rather than high-intensity functions such as headlamps or brake lights.
Because the 12961 is a Philips part number rather than a universal trade number, equivalent bulbs from other manufacturers must share the T10 form factor and W2.1x9.5d base to be considered interchangeable.
The consistent use of a single bulb specification across both front and rear side marker positions indicates that the same replacement unit serves multiple socket locations on the vehicle.