The Mercedes-Benz E420 tail light requires bulb size 12821 or 5008 depending on the specific application. Data for the provided specifications covers the range from 1994 to 1997.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz E420 outer tail light draws from two distinct bulb standards across its model years: the ANSI standard used in the United States and Canada, and the ECE standard used in Europe and worldwide markets.
The 5008 is an ANSI-standard, single-filament bulb with a BA15s bayonet base rated at 12V, and it is specified for the 1994-1995 model years in one of the outer tail light positions.
The 5008 is a lower-wattage variant of the 1156 bulb, meaning the two share the same BA15s bayonet base but are not identical in output and should not be treated as direct substitutes without accounting for the wattage difference.
The P21W is an ECE-standard, single-filament signalling bulb with a BA15s bayonet base rated at 12V and 21W, specified for the 1995 model year in one outer tail light position.
Both the P21W and the 5008 use a BA15s bayonet base, but they originate from different regulatory standards and carry different wattage ratings, which affects their interchangeability.
The 1997 model year outer tail light specification includes two separate bulb positions, one using the 12961 and another using the 12821, both of which are Philips part numbers for miniature wedge bulbs.
The 12961 and 12821 are both T10 miniature wedge bulbs with a W2.1x9.5d base, rated at 12V and 5W, making them functionally equivalent in electrical terms despite carrying different Philips part numbers.
The W2.1x9.5d base designation refers to a wedge-type connection where the bulb is held in place by tension rather than a locking mechanism, which is a common trait of low-wattage indicator and courtesy light applications.
The shift from the BA15s bayonet-based bulbs used in 1994-1995 to the W2.1x9.5d wedge-based T10 bulbs used in 1997 reflects a change in socket type between those model years, meaning bulbs from one generation are not physically compatible with the other.