Audi A8 Dome Light Bulb Size

The Audi A8 dome light bulb uses a H6W size, also designated as 6411 or DE3423. The replacement chart covers vehicle production spanning 1997 to 2010.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2004-2010	H6W
1998-2003	6411
1997	DE3423

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BAX9s base. 12V, 6W.	H6W
ANSI standard (US & Canada). Festoon bulb, 36mm length, SV8.5 base. 12V, 5W.	6411
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V.	DE3423

Other Locations

Additional Notes

The Audi A8 dome light specifications cover model years 1997 through 2010 and reference three distinct bulb types across that span.
The H6W is the most consistently specified bulb in these records, appearing across the 2004-2010 model years. It follows the ECE standard used in Europe and worldwide markets, operates at 12V with a 6W output, uses a BAX9s base, and is a single-filament signalling bulb.
The BAX9s base on the H6W is an offset pin base, meaning the two pins are not positioned symmetrically. This physical characteristic makes it non-interchangeable with standard bayonet or festoon-style bases found in other bulb types listed in these specifications.
The 6411 is specified for the Audi A8 across the 1998-2003 model years. It follows the ANSI standard used in the United States and Canada, operates at 12V with a 5W output, measures 36mm in length, and uses an SV8.5 festoon base with contacts at each end cap.
The DE3423 is specified exclusively for the 1997 Audi A8. It is also an ANSI-standard festoon bulb operating at 12V, but at 41mm in length it is physically longer than the 6411.
The 6411 and DE3423 are both festoon-type bulbs with end-cap contacts, but their differing lengths of 36mm and 41mm respectively make them non-interchangeable in fixed-length dome light housings.
The H6W and the two festoon types (6411 and DE3423) use fundamentally different base designs, which means no cross-substitution is possible between the H6W and either festoon bulb without a socket adapter.
The wattage differs between the H6W (6W) and the 6411 (5W). While both operate on a 12V circuit, substituting one for the other would also require a compatible base, as the electrical ratings alone do not determine interchangeability.
The shift from ANSI-standard festoon bulbs in the earlier model years to the ECE-standard H6W in the 2004-2010 model years reflects a change in the base type and regulatory standard associated with the dome light socket.