The Audi A6 brake light utilizes P21W, 12088, P21/5W, and 1034 bulb sizes depending on the specific version. Data for the provided components spans from 1995 through 2014.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21/5W is the most frequently specified brake bulb across the Audi A6 lineup, covering model years 1995-2001, 2004, and 2006. It follows the ECE standard used in Europe and worldwide, operates at 12V with a dual-filament design rated at 21W and 5W, and uses a BAY15d bayonet base.
The dual-filament configuration of the P21/5W means a single bulb serves two brightness levels within the same housing, with the higher-wattage filament dedicated to the brake function and the lower-wattage filament typically serving a secondary role such as a tail light.
The P21W appears as the specified brake bulb for the Audi A6 in 2007-2008 and 2011-2014. Unlike the P21/5W, it carries a single filament and uses a BA15s bayonet base, making it physically and electrically incompatible with sockets designed for the dual-filament BAY15d base.
The 12088 is a Sylvania OEM part number corresponding to the ANSI 1156 bulb, specified for the Audi A6 in 2009-2010. It shares the same single-filament, BA15s bayonet base construction and 12V/21W rating as the P21W, placing both in the same functional category despite originating from different standardization systems.
The 1034 is an ANSI-standard dual-filament bulb with a BAY15d bayonet base, specified for the 2002 Audi A6. It is described as a variant of the 1157 and carries a 12V, 21/5W rating, making it electrically similar to the P21/5W despite belonging to a different regional standard.
The BAY15d base used by the P21/5W and the 1034 is offset-pin, meaning its two locating pins sit at different heights. This prevents accidental installation of a single-filament BA15s bulb into a dual-filament socket, as the pin geometry differs between the two base types.
The 2723 is a miniature wedge bulb of the T5 form factor, rated at 12V and 1.4W. It is specified exclusively for the Center High Mount Stop Light on the Audi A6 across model years 1995-2004, and its low wattage reflects the reduced power demands typical of supplemental brake lighting in that position.
The P21W and the 12088 (ANSI 1156) share identical base type, voltage, and wattage, but they originate from separate standardization systems, ECE and ANSI respectively. Substitution between them is generally considered feasible when base geometry and electrical ratings match, though fitment should be confirmed against the specific socket design.
The brake bulb specification for the Audi A6 transitions from dual-filament types (P21/5W and 1034) in the 1995-2006 period to single-filament types (P21W and 12088) from 2007 onward, reflecting a change in socket and circuit design across those generation differences.
The P21/5W and the 1034 are not interchangeable with P21W or 12088 bulbs at the socket level, because the BAY15d base requires a housing with two differently positioned pin slots, while the BA15s base fits a simpler single-level socket. Installing a mismatched base type into an incompatible socket is not mechanically possible without modification.