Kawasaki KAF400 Mule SX Brake Bulb Size

The Kawasaki KAF400 Mule SX brake light utilizes a specific P21/5W bulb size for illumination. Data for the bulb specifications covers the range from 2017 to 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
2017-2019	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 P21/5W is the brake bulb type specified for the Kawasaki KAF400 Mule SX across the 2017-2019 model years.
P21/5W is a dual-filament bulb, where the 21W filament serves the brake/stop function and the 5W filament serves a secondary running light function within the same housing.
The bulb operates on a 12V electrical system, consistent with standard automotive and utility vehicle circuitry.
P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement of the BAY15d base prevents incorrect insertion orientation during replacement.
The P21/5W designation follows ECE (Economic Commission for Europe) standards, meaning the bulb specification is recognized across European and international markets rather than being a North American SAE-designated type.
Because the BAY15d base is specific to dual-filament applications, it is not interchangeable with the single-filament BA15s base, which shares a similar appearance but differs in pin configuration.