Citroen DS21 License Plate Bulb Size

The Citroen DS21 license plate light requires a bulb size of 97 for the rear exterior lighting assembly. Data for the specified bulb covers the range from 1969 through 1972.

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
1969-1972	97

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	97

Other Locations

Additional Notes

The bulb size 97 appears across all four model years covered by the Citroen DS21 specifications, spanning 1969-1972, making it the sole license plate bulb type listed for this vehicle.
The 97 is an ANSI-standardized bulb recognized in the US and Canadian markets, operating at 12 volts and rated at 13 watts.
The 97 uses a BA15s bayonet base, which is a single-contact bayonet fitting. The "s" in BA15s denotes a single center contact at the base, as opposed to the dual-contact BA15d variant.
The 97 is a single-filament bulb, meaning it serves one lighting function rather than switching between two brightness levels as a dual-filament bulb would.
The 97 is described as a variant of the 1156 bulb. While the two share the BA15s base and single-filament design, they are not identical, and substituting one for the other without confirming voltage and wattage compatibility carries a risk of incorrect fitment.