Audi A5 Back Up Light Bulb Size

The Audi A5 back up light utilizes a 921 bulb size for the rear illumination system. Data for the specific component covers the range from 2010 through 2014.

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
2010-2014	921

Bulb Specifications

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

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Additional Notes

The Audi A5 uses the 921 bulb size for the back up light across the 2010-2014 model years.
The 921 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard applicable in both the US and Canada.
The 921 bulb uses a wedge-style base, designated T15, which refers to a plastic wedge that slots directly into the socket without requiring a separate metal base or locking mechanism.
The T15 designation indicates the bulb body is 15 units wide in the T-series sizing convention, where each unit equals one eighth of an inch.
The 921 operates at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles.
The 921 is rated at 16 watts, placing it in a moderate output range typical of reverse lighting applications.
Because the 921 is an ANSI-standardized wedge bulb, it is interchangeable with other bulbs sharing the same T15 wedge base and compatible voltage and wattage ratings, provided the replacement meets the original electrical specifications.