Volvo XC40 Back Up Light Bulb Size

The Volvo XC40 back up light requires a specific H21W bulb size for proper installation and function. Data for the bulb size covers the range from 2019 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
2023-2024	H21W
2019-2020	H21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BAY9s base. 12V, 21W.	H21W

Other Locations

Additional Notes

The H21W is the sole bulb type listed across all model years of the Volvo XC40 back up light specifications covered, spanning 2019-2020 and 2023-2024.
The H21W operates at 12 volts with a 21-watt output, classifying it as a single-filament bulb intended for signalling applications rather than illumination.
The H21W uses a BAY9s base, which is an offset bayonet mount. The offset pin arrangement of the BAY9s prevents incorrect installation of a bulb with an incompatible base type.
The H21W is governed by ECE standards, a regulatory framework recognized across Europe and numerous other markets worldwide, distinguishing it from SAE-standard bulbs common in North American applications.
Because the BAY9s base is specific to the ECE signalling family, substitution with physically similar bayonet bulbs using different pin configurations, such as the BA15s or BAY15d, is not compatible with the Volvo XC40 back up light socket.