Suzuki Motorcycle S40 Boulevard Brake Bulb Size

The Suzuki Motorcycle S40 Boulevard uses a brake component requiring a P21/5W bulb size for proper operation. Available information covers a specific time range starting in 2005 and ending in 2019.

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
2011-2019	P21/5W
2005-2009	P21/5W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W

Other Locations

Additional Notes

The Suzuki Motorcycle S40 Boulevard uses the P21/5W bulb type for its brake light across the 2005-2009 and 2011-2019 model years.
The P21/5W is a dual-filament bulb, with one filament rated at 21 watts for the brake or turn signal function and a second filament rated at 5 watts for the tail or parking light function.
This bulb operates on a 12-volt electrical system, which is standard for motorcycle applications.
The P21/5W uses a BAY15d bayonet base, a two-pin offset base design that physically prevents single-filament bulbs from being installed in its place, as the pins are positioned asymmetrically.
The P21/5W is governed by ECE (Economic Commission for Europe) standards, meaning it is recognized and used in European and worldwide markets rather than being exclusive to North American specifications.
Because the BAY15d base is offset, it is not interchangeable with the BA15d base, which shares a similar appearance but has symmetrically placed pins intended for non-polarized dual-filament applications.