The Mercedes-Benz ML320 tail light requires P21W and P21/4W bulb sizes for proper illumination across various production versions. Available data covers a time range from 1998 through 2009.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The two bulb types specified for the Mercedes-Benz ML320 outer tail light are the P21W and the P21/4W, both of which follow ECE standards used across Europe and worldwide markets.
The P21W is a single-filament signalling bulb operating at 12V and 21W, fitted with a BA15s bayonet base.
The P21/4W is a dual-filament signalling bulb operating at 12V with filaments rated at 21W and 4W respectively, fitted with a BAZ15d bayonet base.
Although the P21W and P21/4W share the same 12V operating voltage and a visually similar bayonet-style base, their bases are not identical. The BA15s and BAZ15d bases are keyed differently, meaning the two bulb types are not interchangeable.
The dual-filament design of the P21/4W allows a single bulb to serve two lighting functions simultaneously, such as a running light and a brake or turn signal, within one housing.
For the ML320, model years 1998-2003 use the P21/4W in the outer tail light position across both data sets provided.
The 2007 ML320 outer tail light is listed with both the P21W and the P21/4W across the two data sets, indicating a specification difference that warrants verification against the specific vehicle before fitment.
The 2008 ML320 outer tail light is specified as P21W in both data sets, representing a point of agreement between the two sets of records for that year.
The 2009 ML320 outer tail light is specified as P21W, a fitment that appears only in one of the two data sets provided.