The Audi 80 brake light requires a P21/5W bulb size for proper installation and function. Data for the specific component covers the period from 1988 through 1992.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Audi 80 uses the P21/5W bulb for its brake lights across the 1988-1992 model years.
The P21/5W is an ECE-standard dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve both brake and tail light functions.
The BAY15d bayonet base features offset pins, which physically prevents incorrect installation of a single-filament bulb in place of the dual-filament P21/5W. Substituting a single-filament equivalent would result in loss of one lighting function.
The center high mount stop light on the Audi 80 uses the bulb size 70 across the 1988-1992 model years.
The 70 is an ANSI-standard miniature wedge bulb of the T5 form factor, rated at 12V and 1.4W. Its low wattage reflects its role as a supplementary brake signal rather than a primary light source.
The P21/5W follows ECE regulations, which are applied in Europe and other worldwide markets, while the 70 follows ANSI standards used in the United States and Canada. The presence of both standards in the Audi 80 reflects its international production and distribution context.
The wedge base of the 70 bulb is not interchangeable with the BAY15d bayonet base of the P21/5W. The two bulbs serve separate lighting positions and share no fitment compatibility.