Audi S5 Back Up Light Bulb Size

The Audi S5 back up light utilizes a 921 bulb size for the rear illumination system. Data for the specified component covers the range from 2008 to 2018.

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
2008-2018	921

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921

Other Locations

Additional Notes

The Audi S5 uses the 921 bulb for its back up light across the 2008-2018 model years.
The 921 is a wedge-base bulb, classified under the T15 designation, which refers to its tubular glass envelope size of 15/8 inches in width.
The 921 operates at 12 volts and 16 watts, which is consistent with standard automotive low-voltage electrical systems.
The 921 bulb conforms to ANSI standards recognized in both the United States and Canada, indicating a standardized specification for the North American market.
The wedge base design of the 921 means the bulb is held in place by tension from the socket itself rather than by a separate locking mechanism or bayonet pins.
Because the 921 is an ANSI-standardized wedge bulb, it is physically interchangeable with other bulbs sharing the T15 wedge base, provided the replacement matches the 12V and 16W electrical ratings.