The Porsche Cayenne brake light utilizes a P21W bulb size for illumination across all recorded vehicle versions. Data for the specified component covers the period from 2003 through 2006.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche Cayenne (2003-2006) uses three distinct brake bulb types across its brake light positions: P21W for the standard brake, P21/4W for the inner brake, and P21/5W for the outer brake.
All three bulb types are ECE-standard units, meaning they conform to the Economic Commission for Europe regulatory framework used across Europe and internationally.
The P21W is a single-filament bulb operating at 12V and 21W, fitted with a BA15s bayonet base. Its single filament means it serves one lighting function only.
The P21/4W is a dual-filament bulb rated at 12V with filaments of 21W and 4W, fitted with a BAZ15d bayonet base. The dual-filament design allows it to serve two separate lighting functions within one housing.
The P21/5W is also a dual-filament bulb rated at 12V with filaments of 21W and 5W, fitted with a BAY15d bayonet base. It shares the same wattage on its primary filament as the P21/4W but differs on the secondary filament rating.
The three bulb types each carry a different bayonet base designation: BA15s, BAZ15d, and BAY15d. These bases are not interchangeable, as each has a distinct pin configuration that physically prevents incorrect installation.
The Porsche Cayenne (2003-2006) applies the same bulb specification consistently across all four model years for each brake position, with no variation in bulb type recorded across that period.
The P21/4W and P21/5W share the same primary filament wattage of 21W but differ in their secondary filament output and base type, making them distinct components despite their similar naming convention.