Porsche 944 front turn signal bulbs use P21/5W size while rear turn signal bulbs use P21W size. The replacement chart covers 1983 to 1991 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche 944 front turn signal uses the P21/5W bulb across all model years from 1983-1991.
The P21/5W is a dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The BAY15d base features offset pins, which physically prevents substitution with single-filament bulbs that use a different base configuration.
The Porsche 944 rear turn signal uses the P21W bulb across all model years from 1983-1991.
The P21W is a single-filament bulb rated at 12V at 21W, mounted on a BA15s bayonet base.
The BA15s base used by the P21W and the BAY15d base used by the P21/5W are not interchangeable, as the pin offset on the BAY15d is absent on the BA15s.
Both the P21/5W and P21W conform to ECE standards, a regulatory framework recognized across Europe and numerous other markets worldwide.
The front and rear turn signal positions on the 944 use different bulb types, with the front requiring a dual-filament P21/5W and the rear requiring a single-filament P21W.
The shared 21W output of both bulb types means the turn signal flash rate remains consistent front and rear, as flash rate in standard relay systems is sensitive to circuit wattage.