The Mercedes-Benz S420 front side marker bulb uses 2357NA or 1157 size, while the rear side marker bulb uses P21/5W or P21/4W size. The replacement chart covers 1994 to 1999 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 Mercedes-Benz S420 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 interchangeable 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 relying on a colored lens or housing to filter the light.
The rear side marker on the S420 transitions between two ECE-standard bulb types across its production run, with the P21/4W fitted on 1994-1995 models and the P21/5W fitted on 1996-1999 models.
The P21/5W and P21/4W are both ECE-standard dual-filament signalling bulbs rated at 12V and 21W on the primary filament, differing only in their secondary filament rating of 5W versus 4W respectively.
A critical fitment distinction exists between the P21/5W and P21/4W: the P21/5W uses a BAY15d bayonet base, while the P21/4W uses a BAZ15d bayonet base. These two base types are not interchangeable.
The BAZ15d base on the P21/4W has offset pins at different heights than those of the BAY15d, which physically prevents incorrect installation into a BAY15d socket.
The front side marker sockets on the S420 follow ANSI standards, while the rear side marker sockets follow ECE standards, reflecting a mixed regulatory fitment across the vehicle.