The Mercedes-Benz S350 front fog light uses H7, H1, or H3 bulb sizes, while rear fog light applications require P21/4W or P21W bulb sizes depending on model generation. The replacement chart covers 1994 through 2013 production years with corresponding bulb size specifications for each vehicle generation.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz S350 front fog light specifications reference three distinct bulb types across the listed model years: H7, H1, and H3. Each belongs to the ECE halogen family and shares a 12V, 55W electrical rating, though each uses a different base type.
The H7 bulb, fitted to the S350 front fog lights for 2012-2013, uses a PX26d base and is a single-filament halogen bulb operating at 12V and 55W. It holds ECE approval and is also approved for use in the United States and Japan.
The H1 bulb, specified for the 1995 front fog light, uses a P14.5s base. Like the H7, it is a single-filament halogen bulb rated at 12V and 55W with ECE, US, and Japanese approval.
The H3 bulb, specified for the 1994 front fog light, uses a PK22s base. It shares the same 12V, 55W single-filament halogen construction as the H1 and H7 but is not interchangeable with either due to its distinct base type.
Although the H1, H3, and H7 bulbs share identical voltage and wattage ratings, their base types differ entirely. The PX26d, P14.5s, and PK22s bases are physically incompatible with one another, making cross-substitution between these bulb types impossible without modification.
The 2006 front fog light specification also calls for an H7 bulb, the same type listed for 2012-2013. This means the H7 with PX26d base is the most frequently referenced front fog light bulb across the listed S350 model years.
The rear fog light specifications reference two separate bulb types. The 2006 model year uses a P21/4W, while the 1995 model year uses a P21W. These two bulbs differ in both filament count and base type.
The P21/4W is a dual-filament signalling bulb rated at 12V with a 21W and 4W output, mounted on a BAZ15d bayonet base. The offset pins of the BAZ15d base are a deliberate design feature that prevents incorrect installation.
The P21W is a single-filament signalling bulb rated at 12V and 21W, using a BA15s bayonet base. The BA15s base features symmetrical pins, which distinguishes it from the offset BAZ15d base of the P21/4W. The two bulbs are not interchangeable.
All bulb types listed across both the front and rear fog light specifications for the S350 conform to ECE standards, indicating suitability for European and worldwide markets, with the halogen types additionally carrying US and Japanese approval.