Mercedes-Benz 250S License Plate Bulb Size

The Mercedes-Benz 250S uses a DE3423 bulb size for the license plate light, with this specific bulb designation applying across the model's production run. The replacement chart covers 1966 through 1971 model years and documents the bulb specifications for this vehicle generation.

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
1971	DE3423
1966-1968	DE3423

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V.	DE3423

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Additional Notes

The Mercedes-Benz 250S uses the DE3423 bulb for the license plate position across all listed model years, spanning 1966-1968 and 1971.
The DE3423 is classified as a festoon bulb, a cylindrical lamp type that seats between two end-cap contacts rather than fitting into a socket with a base pin or bayonet mount.
Festoon bulbs are held in place by spring-loaded clips at each end of the housing, meaning the physical length of the bulb is a critical fitment factor.
The DE3423 has a length of 41mm, which must correspond to the span between the contact clips in the license plate lamp housing for proper seating and electrical contact.
The bulb operates at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles of this era.
The DE3423 carries an ANSI designation, indicating it conforms to a standardized specification recognized in the United States and Canada, which governs its physical and electrical characteristics.
Because the DE3423 is an ANSI-standardized part, other festoon bulbs sharing the same 41mm length and end-cap contact configuration are generally considered interchangeable, provided they also match the 12V rating.
Festoon bulbs of differing lengths are not interchangeable, as a shorter bulb will fail to make contact with both clips, and a longer bulb will not seat within the housing.