Porsche Cayman Back Up Light Bulb Size

The Porsche Cayman back up light requires a P21W bulb size for proper installation and function within the rear lighting assembly. Data provided covers the range from 2006 to 2012.

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
2006-2012	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 Cayman uses the P21W bulb for its back up light across the 2006-2012 model years.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework used in European and worldwide automotive lighting applications.
P21W bulbs operate on a 12-volt electrical system and draw 21 watts, which is typical for single-filament signalling applications.
The P21W uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single locating pin on the base collar.
Because the BA15s base is a single-contact design, it is not interchangeable with the BA15d base, which carries two contacts and is used in dual-filament bulbs.
The single-filament construction of the P21W means it is dedicated to one lighting function, which in this application is the reverse light.
The consistent P21W fitment across all listed model years of the Porsche Cayman (2006-2012) indicates no bulb specification change occurred within that production period.