Volvo S90 Back Up Light Bulb Size

The Volvo S90 back up light utilizes H21W and P21W bulb sizes for the rear illumination system. Available data for the specific components covers the period from 1997 through 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
2020-2021	H21W
1997-1998	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BAY9s base. 12V, 21W.	H21W
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The H21W is the backup light bulb type used in the Volvo S90 across the 2020-2024 model years, with the exception of 2022, which is not listed in the specifications.
The H21W operates at 12V and 21W, uses a BAY9s base, and is a single-filament signalling bulb built to the ECE standard used in Europe and worldwide markets.
The 1997-1998 Volvo S90 uses the P21W bulb for the backup light position.
The P21W also operates at 12V and 21W and shares the single-filament ECE signalling design, but it uses a BA15s bayonet base rather than the BAY9s base found on the H21W.
Although the H21W and P21W share identical voltage and wattage ratings, their bases are not the same, making the two bulb types physically incompatible with each other's sockets.
The BAY9s base on the H21W features offset pins, which is a design that prevents incorrect installation by ensuring the bulb can only be seated in one orientation.
The BA15s base on the P21W is a standard single-contact bayonet fitting widely used across automotive lighting applications, distinguishing it from the more application-specific BAY9s base of the H21W.