Acura RSX Back Up Light Bulb Size

The Acura RSX back up light utilizes 921 and 7440 bulb sizes depending on the specific version of the vehicle. Available data for the bulb sizes covers the range from 2002 through 2006.

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
2005-2006	921
2002-2004	7440

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

Other Locations

Additional Notes

The Acura RSX backup light specifications cover two distinct bulb types across the 2002-2006 model years: the 921 and the 7440.
The 7440 is a single-filament wedge bulb in the T20 form factor, rated at 12V and 21W, and it fits the Acura RSX for the 2002-2004 model years.
The 921 is a wedge bulb in the T15 form factor, rated at 12V and 16W, and it fits the 2005-2006 model years.
Both bulb types conform to ANSI standards applicable in the US and Canada.
The T15 and T20 designations refer to the tubular bulb body size, with T20 being physically larger than T15. These two form factors are not interchangeable.
The wattage difference between the two bulbs is notable: the 7440 draws 21W while the 921 draws 16W, meaning the earlier RSX backup lights consumed more power per bulb.
Both bulb types use a wedge base, which is a baseless design where the glass envelope itself is pinched to form the electrical contacts, eliminating a separate metal base.
The shift from the 7440 to the 921 between the 2004 and 2005 Acura RSX represents a change in both bulb size and wattage, making cross-year substitution between these two specifications incorrect.