Suzuki Motorcycle LT-F400F KingQuad FS/FSi Brake Bulb Size

Suzuki Motorcycle LT-F400F KingQuad FS/FSi brake bulb uses a P21/5W size. The replacement chart covers 2008 to 2019 production years with corresponding bulb size specifications.

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
2008-2019	P21/5W

Bulb Specifications

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

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Additional Notes

The Suzuki LT-F400F KingQuad FS/FSi uses the P21/5W bulb type for its brake light across all model years from 2008-2019.
The P21/5W is a dual-filament bulb, meaning it contains two separate filaments within a single glass envelope. The higher 21W filament serves the brake/stop function, while the lower 5W filament handles the tail/running light function.
The P21/5W operates on a 12V electrical system, which is standard for this class of powersport vehicle.
This bulb follows the ECE (Economic Commission for Europe) standard, a regulatory framework recognized across Europe and numerous other markets worldwide.
The P21/5W uses a BAY15d bayonet base. The BAY15d designation indicates an offset dual-contact base, where the two pins are positioned at different heights to prevent incorrect installation of the bulb.
Because the BAY15d base uses asymmetrically placed pins, a bulb with a symmetrical dual-contact base (such as the BA15d) is not a compatible substitute, as it would not seat correctly and could cause incorrect filament activation.