Mercedes-Benz 560SL Back Up Light Bulb Size

The Mercedes-Benz 560SL back up light uses a P21W bulb size for the reverse lighting assembly. The replacement chart covers 1986 through 1989 production years with corresponding bulb specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1986-1989	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The Mercedes-Benz 560SL uses the P21W bulb for its back up light across the 1986-1989 model years.
The P21W is an ECE-standard bulb, meaning it conforms to the European and international regulatory framework for automotive lighting rather than the SAE standards common in North American vehicles.
P21W operates at 12 volts with a 21-watt output, which is a typical rating for single-filament signalling applications such as reverse lights.
The single-filament design of the P21W reflects its dedicated signalling function, as opposed to dual-filament bulbs that serve two lighting roles within one unit.
The P21W uses a BA15s bayonet base, where "BA15" denotes the 15mm bayonet cap and "s" indicates a single contact at the base, distinguishing it from the dual-contact BA15d variant.
The BA15s base type is a critical fitment detail, as substituting a BA15d bulb into a BA15s socket is not possible due to the differing contact configurations.