Porsche Boxster Back Up Light Bulb Size

The Porsche Boxster back up light utilizes a P21W bulb size for illumination purposes. Available data covers the range from 1997 through 2012 for the specified component.

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
1997-2012	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 Porsche Boxster uses the P21W bulb size for the back up light across the 1997-2012 model years.
The P21W is an ECE-regulated bulb type, meaning it conforms to European and international lighting standards rather than SAE standards commonly associated with North American automotive applications.
The P21W operates at 12 volts and 21 watts, which is a standard wattage for single-filament signalling applications in passenger vehicles.
The P21W uses a BA15s bayonet base, where "BA" denotes a bayonet cap fitting, "15" refers to the 15mm base width, and the lowercase "s" indicates a single contact at the base.
As a single-filament bulb, the P21W serves one lighting function only, which is consistent with its role as a dedicated back up light rather than a combined stop or tail light.
The BA15s base is not interchangeable with the BA15d base, which carries two contacts. Substituting a dual-contact bulb in a single-contact socket would result in an improper fit.
The uninterrupted use of the P21W across all sixteen model years of the Porsche Boxster covered in these specifications indicates a consistent back up light socket design throughout that production span.