Mercedes-Benz C240 Back Up Light Bulb Size

The Mercedes-Benz C240 back up light requires a P21W bulb size for proper installation and function within the rear lighting assembly. Data for the specific bulb requirements covers the range from 2001 to 2005.

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
2001-2005	P21W

Bulb Specifications

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

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Additional Notes

The Mercedes-Benz C240 uses the P21W bulb size for the back up light across the 2001-2005 model years.
The P21W is an ECE-standard bulb, meaning it conforms to European and internationally recognized automotive lighting regulations.
P21W bulbs operate on a 12-volt electrical system and draw 21 watts, which is typical for single-filament signalling applications.
The P21W is a single-filament bulb, meaning it serves one lighting function only, as opposed to dual-filament bulbs that handle two functions such as braking and running lights simultaneously.
The P21W uses a BA15s bayonet base, where "BA15" refers to the 15mm bayonet cap width and "s" denotes a single contact at the base, distinguishing it from the dual-contact BA15d variant.
The BA15s single-contact base is not interchangeable with BA15d dual-contact bases, as the pin and contact configurations differ between the two.