Porsche 968 brake bulbs utilize a P21/5W size for standard brake applications and an 891 size for the center high mount stop light, with each bulb serving distinct functions in the vehicle's lighting system. The replacement chart covers 1992 through 1995 production years and details the corresponding bulb size specifications for these brake lighting components.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche 968 uses the P21/5W bulb for brake lighting across all four model years covered, spanning 1992-1995.
The P21/5W is an ECE-standard bulb, meaning it follows European and worldwide signalling regulations rather than North American ANSI standards.
As a dual-filament bulb, the P21/5W serves two functions within a single unit, with the 21W filament handling the brake signal and the 5W filament typically serving as a running or tail light.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement prevents incorrect insertion, ensuring the two filaments are oriented correctly within the housing.
The center high mount stop light (CHMSL) on the Porsche 968 uses the 891 bulb for all model years from 1992-1995.
The 891 is an ANSI-standard single-filament halogen bulb, rated at 12V and 27W, making it a higher-wattage unit than either filament in the P21/5W used elsewhere in the brake circuit.
The 891 uses a PGJ13 base, which is a prefocus-style fitting distinct from the BAY15d bayonet base of the P21/5W. These two base types are not interchangeable.
Because the brake bulbs follow ECE standards and the CHMSL bulb follows ANSI standards, the Porsche 968 brake lighting system draws from two separate regulatory frameworks within the same vehicle.