The Volvo S90 fog light utilizes H21W and H3 bulb sizes for the lighting components. Data for the specific bulbs covers the period from 1997 through 2020.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Volvo S90 front fog light positions for the 1997-1998 model years list two bulb sizes: the 881 and the H3. These represent two different regional standards for the same vehicle position.
The 881 bulb follows the ANSI standard, which governs bulb specifications in the United States and Canada. It uses a PGJ13 base and operates at 12V with a 27W output, making it a relatively low-wattage single-filament halogen type.
The H3 bulb follows the ECE standard, which applies across Europe and other international markets, though it also carries approval for use in the United States and Japan. It uses a PK22s base and operates at 12V with a 55W output, drawing roughly twice the wattage of the 881.
Because the 881 and H3 use different base types, PGJ13 and PK22s respectively, they are not physically interchangeable. The correct fitment depends on which regional specification the individual vehicle was built to.
The rear fog light position on the Volvo S90 for the 2017-2020 model years specifies the H21W bulb across all four years without variation.
The H21W is classified as a signalling bulb rather than an illumination bulb, reflecting its role in rear fog light applications where visibility signalling is the primary function rather than forward lighting output.
The H21W operates at 12V and 21W, using a BAY9s base. The BAY9s is an offset-pin bayonet base, meaning the two pins are positioned asymmetrically to prevent incorrect installation orientation.
The H21W follows the ECE standard and is primarily associated with European and international markets, which aligns with the rear fog light being a legally required feature in those regions.