The Jaguar X-Type brake light utilizes a P21/5W bulb size for the rear lighting system. Data for the specific component covers the range from 2002 through 2008.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Jaguar X-Type uses the P21/5W bulb for brake lighting across all model years from 2002-2008.
The P21/5W is an ECE-standard dual-filament bulb rated at 12V with a 21W brake filament and a 5W running filament, mounted on a BAY15d bayonet base.
The BAY15d base features offset pins, which physically prevents incorrect single-filament bulbs from being seated in its place, as the pin positions are not interchangeable with the single-contact BA15s base.
The 21W filament in the P21/5W activates under braking, while the 5W filament serves as a continuous tail or position light, making the two circuits electrically independent within a single housing.
The Jaguar X-Type (2002-2003) uses a separate bulb type for the Center High Mount Stop Light, designated by the Philips part number 12961.
The 12961 is a T10 miniature wedge bulb rated at 12V and 5W, fitted with a W2.1x9.5d wedge base, which is a single-filament design with no bayonet or pin retention mechanism.
The W2.1x9.5d wedge base of the 12961 is not compatible with the BAY15d bayonet base used by the P21/5W, meaning the two bulb types serve entirely separate sockets and are not interchangeable.
The Center High Mount Stop Light specification for the Jaguar X-Type covers only the 2002-2003 model years, while the standard brake bulb specification spans the full 2002-2008 production range.