Jaguar XJ8 Back Up Light Bulb Size

The Jaguar XJ8 back up light requires a P21W bulb size for proper installation and function within the rear lighting assembly. Provided information covers the span from 1998 through 2009 for the specified vehicle and component.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1998-2009	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The Jaguar XJ8 uses the P21W bulb for the back up light across all listed model years from 1998 to 2009.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework, which governs automotive lighting specifications across European and many worldwide markets.
The P21W operates at 12 volts and 21 watts, which is a standard rating for single-filament automotive signalling applications.
The P21W uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin offset to one side, distinguishing it from the dual-contact BA15d variant.
Because the BA15s base is single-contact, the P21W is not interchangeable with visually similar bulbs that use a BA15d base, as the pin configuration differs.
The single-filament design of the P21W means the bulb serves one dedicated function, in this case the reverse light, rather than combining multiple lighting functions within one unit.
The consistent use of the P21W across the 1998-2009 model range of the Jaguar XJ8 indicates a stable back up light socket specification throughout that production period.