Volkswagen GTI Back Up Light Bulb Size

The Volkswagen GTI back up light utilizes 921, 7440, and P21W bulb sizes depending on the specific vehicle configuration. Data for the provided bulb sizes covers the range from 2006 through 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
2014-2018	921
2010-2013	921 (With LED Tail Lights)
2010-2013	7440 (Without LED Tail Lights)
2006-2009	P21W

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament wedge bulb (T20). 12V, 21W.	7440
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The Volkswagen GTI backup light bulb specifications cover model years 2006-2018 and reference three distinct bulb types: the 921, the 7440, and the P21W.
The 921 is a T15 wedge bulb rated at 12V and 16W, produced to the ANSI standard used in the United States and Canada.
The 7440 is a T20 single-filament wedge bulb rated at 12V and 21W, also built to the ANSI standard. It draws more wattage than the 921, which reflects a higher power output in the backup light circuit.
The P21W follows the ECE standard, which is the regulatory framework used in Europe and much of the rest of the world. It is a single-filament bulb rated at 12V and 21W, and it uses a BA15s bayonet base rather than a wedge-style fitting, making it physically incompatible with sockets designed for the 921 or 7440.
GTI model years 2006-2009 use the P21W exclusively, consistent with European-specification lighting components carried over into those production years.
For the 2010-2013 Volkswagen GTI, the correct backup light bulb depends on whether the vehicle was built with LED tail lights. Units without LED tail lights take the 7440, while units with LED tail lights take the 921.
The split fitment across 2010-2013 means two vehicles of the same model year may require different bulbs, and confirming the tail light configuration before selecting a replacement is necessary for a correct fit.
GTI model years 2014-2018 use the 921 without any noted trim or package variation, indicating a standardized fitment across those years.
The 921 and 7440 are both ANSI wedge-type bulbs but use different base sizes, T15 and T20 respectively, meaning they are not interchangeable despite sharing the same voltage rating.