Mercedes-Benz 230 License Plate Bulb Size

The Mercedes-Benz 230 license plate light uses bulb sizes DE3423 and 12821 according to the provided specifications. Available data covers the range from 1966 through 1978 for the specified vehicle components.

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
1974-1978	DE3423
1968-1969	DE3423
1966-1967	12821

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V.	DE3423
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12821

Other Locations

Additional Notes

The DE3423 is an ANSI-standard festoon bulb rated at 12V, measuring 41mm in length with end-cap contacts at each end. This contact style means the bulb is held in place and powered by spring-loaded holders that press against both ends rather than a socket base.
The 12821 is a Philips part number designating a miniature wedge bulb in the T10 form factor. It uses a W2.1x9.5d base, operates at 12V, and draws 5W.
A wedge base bulb like the 12821 is retained by friction from the socket walls rather than a separate locking mechanism, which is a fundamentally different fitment method from the end-cap festoon design of the DE3423.
The Mercedes-Benz 230 used the DE3423 festoon bulb for license plate illumination across the 1974-1978 model years, as well as the 1968 and 1969 model years.
The 1966 and 1967 model years of the Mercedes-Benz 230 used the 12821 wedge bulb rather than the festoon type found in later and earlier listed years.
Because the DE3423 and 12821 use entirely different base types, festoon and wedge respectively, the two bulbs are not interchangeable without modification to the socket housing.
The DE3423 carries ANSI standardization applicable to the United States and Canada, meaning its physical and electrical specifications conform to a defined North American industry standard rather than a manufacturer-specific designation.
Both bulb types share a 12V operating voltage, which is consistent with the standard electrical system voltage found in passenger vehicles of this era.