Mercedes-Benz S320 front and rear side marker bulbs utilize 2357NA and 1157 sizes for front applications, with P21/5W and P21/4W sizes for rear positions. Replacement specifications in the chart span 1994 to 1999 production years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz S320 front side marker uses the 2357NA bulb for model years 1995-1999, while the 1994 model year uses the 1157 bulb instead.
Both the 2357NA and 1157 are ANSI-standard dual-filament bulbs rated at 12V and share the BAY15d bayonet base, making them physically compatible in terms of socket fitment.
Despite sharing the same BAY15d base, the 2357NA and 1157 differ in wattage output. The 2357NA draws 26.9W on its high filament and 8W on its low filament, while the 1157 draws 21W and 5W respectively.
The 2357NA features natural amber glass, which produces an amber output without requiring an amber-tinted lens or socket. The 1157 uses clear glass and relies on an external amber filter to produce the same color output.
The rear side marker on the S320 transitions between two different bulb types across the model range. The 1994-1995 model years use the P21/4W, while the 1996-1999 model years use the P21/5W.
The P21/4W and P21/5W are both ECE-standard dual-filament bulbs rated at 12V with a 21W primary filament, differing only in their secondary filament output of 4W and 5W respectively.
A critical fitment distinction exists between the P21/4W and P21/5W: the P21/4W uses a BAZ15d bayonet base, while the P21/5W uses a BAY15d bayonet base. These two base types are not interchangeable, as the offset pin positions differ to prevent incorrect installation.
The front side marker bulbs on the S320 follow ANSI standards, while the rear side marker bulbs follow ECE standards, reflecting a mixed regulatory specification across the vehicle's lighting system.
The BAY15d base found on the 1157, 2357NA, and P21/5W is an offset dual-contact bayonet fitting. The offset pin arrangement ensures the bulb is seated in a fixed rotational orientation within the socket.
Substituting a P21/5W for a P21/4W in the 1994-1995 rear side marker position would not be a direct fit, as the differing bayonet base configurations between BAZ15d and BAY15d prevent socket compatibility.