Volvo S70 front fog light bulbs use H1 size while rear fog light bulbs use P21W size. The replacement chart covers 1998 to 2000 vehicle production 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 Volvo S70 uses the H1 bulb for its front fog lights across the 1998-2000 model years.
The H1 is a single-filament halogen bulb operating at 12V and 55W, fitted with a P14.5s base, and is standardized under ECE regulations for use in Europe and worldwide, with approval also extended to the United States and Japan.
The rear fog lights on the S70 use the P21W bulb across the same 1998-2000 model years.
The P21W is a single-filament signalling bulb rated at 12V and 21W, mounted via a BA15s bayonet base, and is likewise governed by ECE standards for international use.
The BA15s bayonet base of the P21W is a single-contact fitting, which is not interchangeable with dual-contact bayonet variants such as the BA15d, despite sharing the same 15mm base width.
The P14.5s base of the H1 is a pin-type single-contact fitting unique to that bulb family, meaning it is not physically compatible with other common halogen base types such as H4 or H7 sockets.
Both bulb types operate on a 12V electrical system, consistent with the standard automotive voltage found in the S70.
The front fog light H1 bulb draws 55W, while the rear fog light P21W draws 21W, reflecting the differing functional roles of illumination versus signalling.