Mercedes-Benz E320 License Plate Bulb Size

Additional Notes

• The Mercedes-Benz E320 license plate bulb specifications cover model years 1994-2009, with two distinct bulb types used across that span.
• The DE3423 is an ANSI-standardized festoon bulb used in the E320 for model years 1994-2007. Festoon bulbs make electrical contact through metal end caps at each end of the tube rather than through a base socket, and the DE3423 has a 41mm length and operates at 12 volts.
• The 12961 is a Philips-designated miniature wedge bulb of the T10 type, used in the E320 for model years 2008-2009. It uses a W2.1x9.5d wedge base, operates at 12 volts, and is rated at 5 watts.
• The T10 wedge base of the 12961 relies on spring tension from the socket to hold the bulb in place, whereas the DE3423 festoon relies on compression between two fixed contact points. These two retention methods are mechanically incompatible with each other.
• Because the 12961 and DE3423 use fundamentally different base types, bulbs from the 1994-2007 fitment are not interchangeable with those from the 2008-2009 fitment, even though both operate on a 12-volt system.
• The DE3423 designation follows ANSI standards recognized in the United States and Canada, meaning bulbs sold under that code by different manufacturers are expected to conform to the same physical and electrical specifications.
• The 12961 designation is specific to Philips and corresponds to a T10 wedge bulb. Equivalent bulbs from other manufacturers may be sold under different part numbers, such as W5W, which shares the same W2.1x9.5d base and 5-watt rating.