Audi TT RS Quattro Back Up Light Bulb Size

The Audi TT RS Quattro back up light requires a bulb size of 921 for the rear lighting assembly. Data for the specified vehicle covers the range from 2012 to 2013.

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
2012-2013	921

Bulb Specifications

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

Other Locations

Additional Notes

The 921 bulb is the specified size for the back up light on the Audi TT RS Quattro across the 2012-2013 model years.
The 921 follows the ANSI standard, which is the classification system used in the United States and Canada to define bulb specifications and performance requirements.
It is a wedge-type bulb, categorized under the T15 designation, where "T" refers to the tubular shape and "15" indicates the width of the base in eighths of an inch.
The 921 operates at 12 volts and draws 16 watts, which is consistent with standard automotive low-voltage electrical systems.
The wedge base design means the bulb is held in place by tension from the socket contacts rather than a bayonet or screw mechanism, making it a direct friction-fit installation.