The Mercedes-Benz S500 front fog light utilizes H7, H1, or H3 bulb sizes, while rear fog light applications require P21/4W or P21W bulb sizes depending on production specifications. The replacement chart covers 1994 through 2006 model years with corresponding bulb size data for each vehicle generation.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
P21/4W(For vehicle with Special protection, Excluding A 159651 - A 192207 With Phone Handset In Rear Armrest With Phone Handset In Rear Armrest, To ID A 192208)
Bulb Specifications
Description
Bulb Size
ECE standard (Europe & worldwide). Single-filament halogen bulb with PX26d base. Also approved in the US and Japan. 12V, 55W.
The Mercedes-Benz S500 front fog light specifications cover three distinct halogen bulb types across the listed model years: H7, H1, and H3. All three share the same ECE standard rating of 12V and 55W, though each uses a different base type.
The H7 bulb uses a PX26d base and fits the front fog lights on the 2003-2006 S500. It is a single-filament halogen bulb approved under ECE standards as well as in the US and Japan.
The H1 bulb uses a P14.5s base and fits the front fog lights on the 1998-2002 S500. Like the H7, it is a single-filament halogen bulb rated at 12V, 55W, with ECE, US, and Japanese approval.
The H3 bulb uses a PK22s base and is specified for the front fog light on the 1994 S500. It is also a single-filament halogen bulb at 12V, 55W. The base type differs from both the H1 and H7, making these three front fog bulbs non-interchangeable despite sharing identical voltage and wattage ratings.
The rear fog light on the 2000-2006 S500 uses the P21/4W bulb exclusively. This is a dual-filament signalling bulb with a BAZ15d bayonet base, rated at 12V with a 21W main filament and a 4W secondary filament.
For the 1995-1999 S500, the rear fog light specification branches into two fitments. Vehicles with special protection and production IDs up to A 192208, excluding the range A 159651 through A 192207 with a phone handset in the rear armrest, use the P21/4W bulb. All other vehicles in those years use the P21W.
The P21W bulb is a single-filament signalling bulb with a BA15s bayonet base, rated at 12V, 21W. Its base type differs from the P21/4W, which uses a BAZ15d base. The offset pin arrangement on the BAZ15d base prevents incorrect installation of a P21W in a P21/4W socket.
The P21/4W and P21W are not interchangeable. Although both operate at 12V and share a similar physical profile, the difference in base design and filament configuration means substituting one for the other is not supported by the specifications.
The front fog light bulb type on the S500 changed twice across the listed production span, moving from H3 in 1994 to H1 for 1998-2002, then to H7 for 2003-2006. Each transition involved a different base type, so bulbs from one era are not compatible with housings from another.
All five bulb types listed across both fog light positions conform to ECE standards, indicating they are designed for international use and carry approval for markets including the US and Japan.