Freightliner Sprinter Tail Light Bulb Size

The Freightliner Sprinter tail light requires a P21/5W bulb in 12821 size. A replacement chart covering 2002 through 2021 model years documents the bulb specifications for this vehicle.

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
2019-2021	P21/5W (With Halogen Capsule Headlamps)
2010-2018	P21/5W
2007-2009	12821
2002-2006	P21/5W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12821

Other Locations

Additional Notes

The P21/5W is the dominant tail light bulb type across the Freightliner Sprinter's specification range, appearing in 17 of the 20 model years listed, spanning 2002-2006 and 2010-2021.
The P21/5W is an ECE-standard dual-filament bulb operating at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve both tail light and brake light functions.
The BAY15d bayonet base uses an offset pin arrangement to prevent incorrect installation, ensuring the two filaments are oriented correctly within the housing.
The 2007-2009 Freightliner Sprinter uses the 12821 bulb instead of the P21/5W. The 12821 is a Philips part number for a miniature wedge-type bulb with a W2.1x9.5d base, rated at 12V and 5W, which is a single-filament design.
The BAY15d base of the P21/5W and the W2.1x9.5d wedge base of the 12821 are physically incompatible, meaning the two bulb types are not interchangeable between model years.
For the 2019-2021 Freightliner Sprinter, the P21/5W specification is conditional, applying specifically to vehicles equipped with halogen capsule headlamps rather than all trim configurations.
The single-filament 5W rating of the 12821 contrasts with the dual-filament 21W/5W output of the P21/5W, reflecting a functional difference in how the tail light circuit was designed across different production years.
Substituting a P21/5W for a 12821, or vice versa, would require a base adapter or socket modification, as neither bulb's base is compatible with the other's housing.