Mercedes-Benz CLK63 AMG Back Up Light Bulb Size

The Mercedes-Benz CLK63 AMG back up light requires a P21W bulb size for proper installation and function. Data for the specified component covers the range from 2007 to 2008.

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
2007-2008	P21W

Bulb Specifications

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

Other Locations

Additional Notes

The P21W is the sole bulb type specified for the Mercedes-Benz CLK63 AMG backup light across the 2007-2008 model years.
The P21W is an ECE-standard single-filament signalling bulb rated at 12 volts and 21 watts.
It uses a BA15s bayonet base, which is a single-contact base with a 15mm collar and one locating pin, distinguishing it from visually similar bases such as the BA15d, which carries two pins.
The single-filament design of the P21W means it serves one lighting function only, making it distinct from dual-filament bulbs used in combined stop and tail applications.
The BA15s base type is not universally interchangeable with other bayonet bases, and substituting a bulb with a different base configuration would result in an improper fit.
The ECE designation indicates the P21W conforms to United Nations Economic Commission for Europe regulations, a standard adopted across European and many worldwide markets.