Citroen DS21 headlight bulbs utilize H5001 size for high beam and H5006 size for low beam applications. The replacement chart covers 1969 through 1972 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 Citroen DS21 uses two distinct sealed beam types across its 1969-1972 model years: the H5001 for high beam and the H5006 for low beam headlights.
Both the H5001 and H5006 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When the filament fails, the entire unit requires replacement rather than just an internal bulb.
The H5001 is a 4-inch square sealed beam unit operating at 12 volts, conforming to ANSI standards applicable in the United States and Canada.
The H5006 is a 5.75-inch round sealed beam unit, also rated at 12 volts and built to the same ANSI standard. Its round form factor differs physically from the square H5001, making the two units non-interchangeable despite sharing the same voltage rating.
The ANSI standardization of both units means physically compatible replacements from multiple manufacturers are generally available, provided the correct type designation is matched.
The consistent use of H5001 and H5006 across all four model years indicates no changes were made to the headlight bulb specifications for the DS21 during the 1969-1972 period.