Mercedes-Benz SLK230 Back Up Light Bulb Size

The Mercedes-Benz SLK230 back up light utilizes a P21W bulb size for the specific lighting component located at the rear of the vehicle. Data for the bulb size covers the range from 1998 through 2004.

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
1998-2004	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 Mercedes-Benz SLK230 uses the P21W bulb size for the back up light across all listed model years, spanning 1998-2004.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework, which governs lighting equipment used in European and worldwide automotive markets.
The P21W operates at 12 volts and 21 watts, which is a standard rating for single-filament signalling applications such as reverse lights.
As a single-filament bulb, the P21W serves one dedicated function per unit, distinguishing it from dual-filament types that handle two lighting functions through separate filaments within the same housing.
The P21W uses a BA15s bayonet base, where "BA15" refers to a 15mm bayonet cap and the "s" denotes a single-contact configuration, meaning the electrical circuit is completed through one contact pin at the base.
The BA15s base type is not interchangeable with the BA15d base, which carries a dual-contact configuration. Substituting a BA15d bulb in a BA15s socket would result in improper fitment.