Jaguar XJ12 front fog light bulbs use H3 size while rear fog light bulbs use P21W size. The replacement chart covers 1994 to 1996 model years 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 front fog light uses the H3 bulb across the 1994-1996 model years.
The H3 is a single-filament halogen bulb operating at 12V and 55W, fitted with a PK22s base, and is classified under the ECE standard used in Europe and worldwide, with additional approval in the United States and Japan.
The PK22s base is a pinch-type connector, which is physically distinct from bayonet and screw-type bases and is not interchangeable with them.
The Jaguar XJ12 rear fog light uses the P21W bulb for the 1995-1996 model years.
The P21W is a single-filament signalling bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and also falls under the ECE standard.
The BA15s base uses a single-contact bayonet fitting, which is not compatible with dual-contact bayonet bases such as the BA15d, making base type a critical factor when sourcing a replacement P21W.
The H3 and P21W bulbs serve different functions and carry different wattage ratings, 55W and 21W respectively, meaning the two types are not interchangeable with each other.
Both the H3 and P21W operate on a 12V electrical system, consistent with the standard automotive voltage found in the XJ12.