Subaru Crosstrek Back Up Light Bulb Size

The Subaru Crosstrek back up light utilizes 1157, 7440, and 921 bulb sizes depending on the specific version of the vehicle. Data for the provided components covers the range from 2017 to 2024.

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
2024	1157
2018-2023	7440
2017	921

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V, 21W/5W.	1157
ANSI standard (US & Canada). Single-filament wedge bulb (T20). 12V, 21W.	7440
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921

Other Locations

Additional Notes

The 7440 bulb is the most frequently specified backup light for the Subaru Crosstrek, covering the 2018-2023 model years across six consecutive years.
The 7440 is a single-filament T20 wedge bulb rated at 12V and 21W, conforming to ANSI standards for the US and Canadian markets.
The 2024 Subaru Crosstrek requires a 1157 bulb, which differs fundamentally from the 7440 used in prior years. The 1157 uses a BAY15d bayonet base rather than a wedge-style fit, making the two bulbs physically incompatible with each other.
The 1157 is a dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, whereas the 7440 carries only a single filament at 21W.
The 2017 Crosstrek uses a 921 bulb, a T15 wedge type rated at 12V and 16W. Although the 921 shares the same wedge-style base as the 7440, its lower wattage and smaller T15 housing distinguish it from the T20 form of the 7440.
The 921 and 7440 are both wedge-base bulbs, but their differing physical sizes mean they are not interchangeable without risk of an improper fit in the socket.
All three bulb types listed in the specifications, the 1157, 7440, and 921, operate on a 12V electrical system and comply with ANSI standards applicable in both the United States and Canada.
The shift from the 921 in 2017 to the 7440 in 2018 represents a change in both wattage output and bulb housing size for the backup light position.