Ski-Doo Expedition Sport ACE 900 Tail Light Bulb Size

The Ski-Doo Expedition Sport ACE 900 tail light utilizes a P21/5W bulb size for the lighting component. Available data for the specified equipment covers the range from 2014 to 2018.

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
2014-2018	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 P21/5W is the sole tail light bulb type listed for the Ski-Doo Expedition Sport ACE 900 across the 2014-2018 model years.
The P21/5W is a dual-filament bulb, meaning it contains two separate filaments within a single glass envelope, one rated at 21W and one at 5W, allowing it to serve both braking and running light functions from a single unit.
The bulb operates on a 12V electrical system, which is standard for this class of powersport vehicle.
The P21/5W uses a BAY15d bayonet base, a two-pin offset base design where the two pins are positioned at different heights to prevent incorrect insertion and ensure correct filament orientation.
The P21/5W is governed by ECE (Economic Commission for Europe) standards, indicating it is a globally recognized specification used across European and international markets rather than a proprietary or region-specific type.
Because the BAY15d base uses offset pins, it is not interchangeable with the BAY15s base, which is a single-filament variant with pins at equal heights. Substituting a BAY15s bulb into a BAY15d socket is not possible without modification.