Porsche Boxster front fog light bulbs use H8 size, while rear fog light bulbs use P21/4W, P21W, or PY21W sizes. The replacement chart covers vehicle production years spanning 1997 to 2012 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 Porsche Boxster uses the H8 bulb for the front fog light across the 2005-2012 model years. The H8 is a single-filament halogen bulb rated at 12V and 35W, fitted with a PGJ19-1 base and built to ECE standards, with approval also extended to the US market.
The rear fog light on the Porsche Boxster uses several different bulb types depending on the model year, reflecting a change in specification between earlier and later production runs.
For the 1997-2003 model years, the Boxster rear fog light takes the P21W, a single-filament signalling bulb with a BA15s bayonet base, rated at 12V and 21W. The 2004 model year also lists the P21W as one of its rear fog light bulbs.
The BAU15s base used by the PY21W is offset, meaning it is not interchangeable with the BA15s base of the P21W despite both bulbs sharing the same 12V, 21W rating. Substituting one for the other is not physically possible without modification.
The 2003 and 2004 model years list both a P21W (white) and a PY21W (yellow/amber) for the rear fog light position, indicating that two bulbs occupy that circuit in those years.
The PY21W is an amber single-filament signalling bulb with a BAU15s bayonet base, rated at 12V and 21W. Its amber output is produced by the glass envelope rather than a coating, which is a standard characteristic of the PY21W type.
From 2005 onward, the rear fog light specification shifts to the P21/4W, a dual-filament signalling bulb with a BAZ15d bayonet base rated at 12V, 21W/4W. The BAZ15d base is distinct from both the BA15s and BAU15s bases used in earlier rear fog light bulbs on this vehicle.
The P21/4W's dual-filament design, producing both a 21W and a 4W output, distinguishes it functionally from the single-filament P21W and PY21W types used in prior model years. These bulb families are not interchangeable due to differing base designs and filament configurations.
All four bulb types specified across both fog light positions on the Boxster conform to ECE standards, which govern bulb performance, base coding, and light output for road use in Europe and other markets that adopt ECE regulations.
The H8's PGJ19-1 base is part of the PGJ19 family of bases used in lower-wattage halogen bulbs. It is not compatible with other members of that family, such as the PGJ19-2 used by the H11, despite a similar physical appearance.