Audi A3 brake bulb sizes include 921 and 7506 for inner positions, with P21W and 7506 specifications for outer brake applications. The replacement chart covers vehicle production years spanning 2006 to 2024 with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Audi A3 brake bulb specifications cover two distinct positions: a general brake light position and an outer brake position, each with its own fitment history.
The 921 bulb is an ANSI-standard wedge bulb (T15) rated at 12V and 16W, used in the general brake position of the Audi A3 from 2014-2021, with a conditional fitment note for 2014-2016 models specifying compatibility with Halogen Capsule Headlamps.
The 7506 bulb appears in both brake positions across the specifications. It serves the general brake position from 2006-2013 and transitions into the outer brake position for 2019-2021.
The P21W is an ECE-standard single-filament signalling bulb with a BA15s bayonet base, rated at 12V and 21W. It is specified for the outer brake position on the Audi A3 from 2022-2024.
The 921 and P21W bulbs differ in both base type and wattage. The 921 uses a wedge base and draws 16W, while the P21W uses a BA15s bayonet base and draws 21W, making the two types non-interchangeable.
The 2016 Audi A3 general brake position carries a conditional fitment note for Halogen Capsule Headlamps, indicating that headlamp configuration is a relevant variable for correct bulb selection on that model year.
The outer brake position on the 2019 Audi A3 carries a fitment note specifying compatibility without special body measures and with a standard tail assembly, indicating that body or trim variations on that year may affect bulb applicability.
The transition from the 921 to the 7506 in the general brake position occurs between the 2013 and 2014 model years, representing a change in ANSI bulb type within the same position.
The outer brake position shifts from the 7506 to the P21W between the 2021 and 2022 model years, marking a change from an ANSI-standard bulb to an ECE-standard bulb in that position.
The BA15s bayonet base of the P21W is a single-contact base, which is mechanically distinct from the wedge base of the 921 and the base configuration of the 7506, reinforcing that these bulb types are not physically interchangeable across positions or model years.