Audi Q3 Back Up Light Bulb Size

Additional Notes

• The 921 bulb is the sole back up light bulb type listed across all model years of the Audi Q3 covered by these specifications, spanning 2015-2024.
• The 921 is classified as a T15 wedge bulb, meaning it uses a wedge-shaped plastic base rather than a metal screw or pin base to secure itself within the socket.
• The bulb operates at 12 volts and draws 16 watts, which is consistent with standard low-voltage automotive electrical systems.
• The 921 designation conforms to ANSI standards recognized in both the United States and Canada, indicating a standardized specification for physical and electrical characteristics.
• The T15 designation refers to the bulb's tubular envelope width, expressed in eighths of an inch, placing it at 15/8 inches wide.
• Because the 921 is an ANSI-standardized wedge type, it is generally interchangeable with other bulbs sharing the same T15 wedge base and compatible voltage and wattage ratings, provided those substitutes meet the same electrical parameters.
• For the Audi Q3, substituting a bulb with a wattage rating higher than 16W risks exceeding the thermal and electrical tolerances of the socket and associated wiring.