The Porsche Carrera GT front inner turn signal requires a 12496 or PY21W bulb size, while the rear turn signal uses a PY21W bulb size. The replacement chart covers 2004 to 2005 model years with corresponding bulb size specifications for each signal location.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche Carrera GT uses two distinct bulb types across its turn signal positions: the PY21W, an ECE-standardized amber single-filament bulb, and the 12496, a Philips/Osram specialty halogen part number.
The PY21W is the more widely used of the two, appearing in the rear turn signal position for both the 2004 and 2005 model years, as well as the 2004 front inner turn signal.
The PY21W operates at 12V with a 21W output and uses a BAU15s bayonet base. The BAU15s base features an offset pin configuration, which physically prevents substitution with the more common BA15s base found on non-amber single-filament bulbs.
The amber coloring of the PY21W is built into the glass envelope itself rather than applied as a coating, which is a requirement under ECE regulations for type-approved amber signal bulbs.
The 2005 Porsche Carrera GT front inner turn signal position specifies the 12496 rather than the PY21W used in the same position on the 2004 model, indicating a mid-production change in that specific fitment.
The 12496 is a Philips and Osram part number designation for a 12V specialty halogen bulb intended for specific automotive applications, and it is not an ECE type designation in the way PY21W is.
Because the 12496 and PY21W are distinct part types with different base configurations and classification origins, they are not interchangeable with one another despite both operating at 12V.