The Mercedes-Benz 560SEC uses a P21/5W bulb size for front turn signals and a P21W bulb size for rear turn signals. The replacement chart covers 1986 to 1991 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 Mercedes-Benz 560SEC uses two distinct bulb types across its turn signal positions: P21/5W at the front and P21W at the rear, both conforming to ECE standards recognized across Europe and worldwide markets.
Both bulb types operate on a 12-volt electrical system, which is standard for automotive lighting applications of this era.
The P21/5W is a dual-filament bulb, meaning it carries two separate filaments within a single envelope, rated at 21 watts and 5 watts respectively.
The P21W is a single-filament bulb rated at 21 watts, serving solely as a turn signal source at the rear without a secondary filament for an additional function.
The P21/5W uses a BAY15d bayonet base, which features two offset pins at different heights to prevent incorrect installation of the dual-filament bulb in the wrong orientation.
The P21W uses a BA15s bayonet base, a single-contact fitting with two pins at the same height, reflecting its single-filament design.
Because the P21/5W and P21W use physically different base types, BAY15d and BA15s respectively, the two bulbs are not interchangeable between the front and rear turn signal positions.
The front turn signal specification of P21/5W remained unchanged across the full 1986-1991 production run of the 560SEC.
The rear turn signal specification of P21W was equally consistent across the same 1986-1991 model years.