The Saab 900 side marker utilizes a 12961 bulb size for illumination purposes within the lighting assembly. Data for the specific component covers the range from 1995 through 1998.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The two most common bulb types across the Saab 900 side marker specifications are the P21/5W and the T10 wedge form factor, with P21/5W appearing in the majority of positions across the full model range.
The P21/5W is an ECE-standard dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, fitted with a BAY15d offset bayonet base. The offset pins on the BAY15d base prevent incorrect single-filament bulbs from being seated in its place.
The 12961 and 12821 are both Philips part numbers for T10 miniature wedge bulbs sharing the W2.1x9.5d base and a 12V, 5W rating. Despite carrying different part numbers, their electrical and physical specifications are identical.
Because the 12961 and 12821 share the same base type, voltage, and wattage, they are interchangeable in practice, though fitment should be confirmed against the specific socket housing in the vehicle.
The Saab 900 front side marker uses the 12961 (T10 wedge) for model years 1994-1998, while the same position on 1981-1993 models calls for the P21/5W dual-filament bayonet bulb. These two bulb types are not interchangeable due to differing base designs and wattage ratings.
The BAY15d bayonet base of the P21/5W is physically and electrically incompatible with the W2.1x9.5d wedge base of the T10 bulbs. Substituting one type for the other is not possible without modifying the socket.
The rear side marker of the Saab 900 uses the P21/5W across 1983-1998, while 1981-1982 models use the 12821, a single-filament T10 wedge bulb rated at only 5W total. The wattage difference between these two types is substantial, with the P21/5W drawing up to 21W on its primary filament.
The front and rear side marker positions share the same bulb type only on 1981-1993 models, where both positions use the P21/5W. From 1994 onward, the front and rear positions require different bulb types.
The P21/5W is classified under ECE regulations and is widely used in European automotive lighting. Its dual-filament design is typically employed in applications requiring both a running light function and a brighter signalling function from a single bulb.
The T10 wedge format used by both the 12961 and 12821 is a single-filament design, making it unsuitable as a direct replacement in any socket originally wired to utilize both filaments of a P21/5W.