BMW 318i Dome Light Bulb Size

Additional Notes

• The 6411 is the most frequently specified dome light bulb across the BMW 318i model years listed, appearing in seven of the nine entries.
• The 6411 is a festoon-type bulb with a 36mm length, an SV8.5 base, and operates at 12V with a 5W rating under the ANSI standard applicable to the US and Canada.
• The DE3423 is also a festoon-type bulb rated at 12V under the same ANSI standard, but it measures 41mm in length and uses end-cap contacts rather than an SV8.5 base.
• Festoon bulbs are cylindrical lamps that make contact at both ends of the housing, a form factor common in automotive interior lighting applications.
• The SV8.5 base on the 6411 and the end-cap contact design on the DE3423 represent physically distinct mounting configurations, meaning the two bulbs are not directly interchangeable despite both being festoon types.
• The BMW 318i (1996-1997) is specified with the DE3423, while the 1993-1994 and 1997-1998 entries revert to or retain the 6411, reflecting a socket configuration difference across those production years.
• The 5mm difference in length between the 6411 and the DE3423 is a relevant fitment factor, as festoon bulbs must match the span of the lamp holder to seat correctly and maintain electrical contact.
• The 6411 carries an explicit 5W power rating in the provided specifications, whereas the DE3423 entry lists no wattage value.