The Jaguar XJ12 high beam headlight bulb size measures 9005 or H5001, while the low beam headlight bulb size measures 9006 or H5006. The replacement chart covers vehicle production years spanning 1973 to 1996 with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Jaguar XJ12 uses four distinct bulb types across its headlight specifications: the 9005, 9006, H5001, and H5006, all conforming to ANSI standards recognized in the United States and Canada.
The 9005 and 9006 are single-filament halogen bulbs operating at 12V. The 9005 is rated at 65W and uses a P20d base, while the 9006 is rated at 55W and uses a P22d base. These two base types are not interchangeable despite their similar designations.
For the 1994-1996 Jaguar XJ12, the 9005 serves the high beam position and the 9006 serves the low beam position. In both cases, only the bulb itself is replaced, not the housing unit.
The H5001 and H5006 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit requires replacement rather than just an internal bulb.
The H5001 is a 4-inch square sealed beam unit rated at 12V and fills the high beam position on the 1973-1979 XJ12. The H5006 is a 5.75-inch round sealed beam unit also rated at 12V and fills the low beam position for the same model years.
The physical form factors of the H5001 and H5006 differ significantly from each other, as one is square and the other is round, making them non-interchangeable between the high and low beam positions.
The transition from sealed beam units to discrete halogen bulbs between the 1979 and 1994 model years reflects a fundamental difference in headlight construction, and components from one era are not compatible with the other.
All four bulb types across both eras operate on a 12V electrical system, which is consistent throughout the XJ12 headlight specifications.