The Jaguar XJS front turn signal requires a P21W bulb size, while the rear turn signal uses a 1156 bulb size. The replacement chart covers vehicle production spanning 1976 to 1996 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Jaguar XJS front turn signal uses two distinct bulb types across its production span, with the 1157 fitted to 1976-1991 models and the P21W fitted to 1992-1996 models.
The 1157 is an ANSI-standard dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. Its dual-filament design means it is physically and electrically distinct from single-filament alternatives.
The P21W is an ECE-standard single-filament bulb rated at 12V, 21W, mounted on a BA15s bayonet base. It is the European and worldwide signalling standard and replaced the 1157 in the XJS front turn signal position from 1992 onward.
Although the 1157 and P21W share a 21W rating, they are not interchangeable. The 1157 uses a BAY15d base with offset locating pins, while the P21W uses a BA15s base with symmetrical pins, making physical substitution between the two impossible without modification.
The rear turn signal on the Jaguar XJS uses the 1156 across the full 1976-1996 model range, making it the only turn signal position with no bulb type change throughout the vehicle's production.
The 1156 is an ANSI-standard single-filament bulb rated at 12V, 21W, mounted on a BA15s bayonet base. Its single-filament construction distinguishes it from the dual-filament 1157 used at the front on earlier models.
The 1156 and P21W share the same BA15s bayonet base and identical wattage rating of 21W at 12V. However, one is an ANSI-standard designation and the other is an ECE-standard designation, and cross-standard substitution warrants verification of exact base tolerances before use.
The front turn signal bulb change from the 1157 to the P21W between the 1991 and 1992 XJS also represents a shift from a dual-filament to a single-filament configuration, which affects circuit behavior if the housing or wiring was designed around the 1157's secondary filament.