Porsche Boxster front and rear turn signal bulbs utilize PY21W, 12496, and P21W sizes depending on generation and location. The replacement chart covers 1997 through 2016 model 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 PY21W is the most frequently specified bulb across the Porsche Boxster turn signal data, appearing in both front and rear positions across multiple model years. It is an ECE-standard single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s offset bayonet base.
The P21W shares the same 12V, 21W rating as the PY21W but uses a BA15s straight bayonet base rather than the offset BAU15s base. This difference in base geometry makes the two bulbs physically non-interchangeable despite their otherwise similar electrical ratings.
The Porsche Boxster front turn signal used the P21W from 1997-2004, after which the specification shifted to PY21W for 2005-2006, then to the 12496 for 2007-2012, before returning to PY21W for 2013-2016.
The 12496 is a Philips/Osram part number designation for a 12V halogen bulb intended for specialty automotive applications. It appears as the front turn signal specification for the Boxster from 2007-2012.
The 12185 is a Philips part number for a 12V halogen bulb and is specified exclusively for the rear turn signal position on the Boxster from 2009-2012.
The rear turn signal specifications show considerable variation across model years, with the P21W, PY21W, 12496, and 12185 each appearing at different points, meaning the rear position does not share a consistent bulb type with the front across the same model years.
Because the BAU15s base of the PY21W and the BA15s base of the P21W are physically distinct, substituting one for the other in positions where a specific type is required would result in an incorrect fit.
Both the PY21W and P21W conform to ECE regulations, which are applied in European and worldwide markets. The amber coloration of the PY21W is built into the bulb itself, whereas the P21W produces clear light and relies on a colored lens for amber output where required.