Mercedes-Benz C300 Tail Light Bulb Size

The Mercedes-Benz C300 outer tail light and tail light utilize a P21W bulb size. The replacement chart covers 2008 to 2011 model year specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Outer Tail Light

Years	Bulb Size
2008-2011	P21W

Years	Bulb Size
2008-2010	P21W

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

The P21W is the sole bulb type listed across all outer tail light positions for the Mercedes-Benz C300, covering model years 2008-2011.
The P21W operates at 12 volts with a 21-watt output, classifying it as a single-filament bulb intended for signalling functions such as tail and brake lighting.
P21W bulbs use a BA15s bayonet base, which is a single-contact fitting. This base type is not interchangeable with BA15d, the dual-contact variant, despite the two sharing an identical physical collar size.
The P21W designation follows ECE (Economic Commission for Europe) standardization, meaning the bulb conforms to internationally recognized performance and construction requirements used across European and worldwide automotive markets.
Because the P21W is a single-filament design, it serves one lighting function per bulb. Assemblies requiring separate brake and tail functions at the same position would use a dual-filament alternative, which the P21W is not.