Mercedes-Benz S400 high beam headlight bulbs use H9 and H7 sizes, while low beam headlight bulbs use D1S size. The replacement chart covers 2010 to 2013 vehicle production 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 H9 bulb is a single-filament halogen type operating at 12V and 65W, built to ECE standards and approved for use in the US. It uses a PGJ19-5 base and serves as the high beam headlight bulb in the Mercedes-Benz S400 for 2011-2013.
The 2010 S400 uses an H7 bulb for the high beam headlight rather than the H9 found in later years. Although both are single-filament halogen bulbs operating at 12V and following ECE standards, the H7 runs at 55W and uses a PX26d base, making it physically and electrically incompatible with the H9 socket.
The PGJ19-5 base of the H9 and the PX26d base of the H7 are distinct fittings. A bulb with one base type cannot be substituted into a socket designed for the other without modification.
The D1S is an HID (xenon) discharge bulb rated at 85V and 35W, operating on a fundamentally different electrical principle than the halogen bulbs used in the high beam position. It uses a PK32d-2 base and incorporates an integral ignitor, which is required to initiate the high-voltage arc that produces light.
The D1S is specified for projector-type housings, meaning the low beam headlight assemblies on the S400 across all listed years (2010-2013) are designed around a projector optical system rather than a reflector-based one.
Because the D1S includes an integral ignitor, it is not interchangeable with other HID bulb types such as the D1R, even though both share a similar voltage and wattage rating. The ignitor placement and base configuration differ between those types.
The low beam position uses the D1S across all four model years (2010-2013), while the high beam position changed from H7 in 2010 to H9 in 2011, indicating a specification revision between those model years.
The H9 draws 65W compared to the H7's 55W. Substituting an H9 into a circuit designed for an H7 would place a higher electrical load on that circuit, independent of the base incompatibility already present between the two types.