The Audi S8 side marker requires a bulb size of 12961 for the lighting assembly. Data for the specific component covers the range from 2001 through 2003.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 2001-2003 Audi S8 front side marker uses the 2357NA bulb, an ANSI-standard type recognized in both the United States and Canada.
The 2357NA is a dual-filament bulb rated at 12V with a high filament draw of 26.9W and a low filament draw of 8W, mounted on a BAY15d bayonet base.
The natural amber glass of the 2357NA produces its amber color through the glass itself rather than through a colored lens or housing.
The BAY15d bayonet base on the 2357NA features offset pins, which physically prevents installation in a single-filament socket designed for a similar base type.
The 2003 Audi S8 rear side marker takes the Philips 12821, while the 2001-2002 model years take the Philips 12961.
Both the 12821 and 12961 are T10 miniature wedge bulbs sharing the W2.1x9.5d base type and identical electrical ratings of 12V at 5W, though they carry different Philips part numbers.
Because the 12821 and 12961 share the same base type and wattage, the physical and electrical similarity between them is notable, yet the specifications list them as distinct part numbers for different model years of the Audi S8 rear side marker position.
The T10 wedge base on both rear side marker bulbs is a push-in type with no locking mechanism, relying on friction from the socket walls to remain seated.