Mercedes-Benz C63 AMG Dome Light Bulb Size

Additional Notes

• The Mercedes-Benz C63 AMG dome light specifications reference two distinct bulb types across the listed model years: the 12961 and the 6411.
• The 6411 is an ANSI-standardized festoon bulb, meaning it is held in place by spring-loaded contacts at each end rather than a socket. It measures 36mm in length and uses an SV8.5 base, operating at 12V and 5W.
• The 12961 is a Philips part number designating a miniature wedge-style bulb in the T10 form factor. It uses a W2.1x9.5d base, which is a pin-type wedge base that friction-fits directly into a socket, and it also operates at 12V and 5W.
• Although both bulb types share identical voltage and wattage ratings, their physical form factors and base types are not interchangeable. A festoon bulb with an SV8.5 base cannot be substituted into a socket designed for a T10 wedge base, and vice versa.
• The 6411 festoon bulb is specified for the C63 AMG across 2008-2009 and 2011-2014.
• The 12961 T10 wedge bulb is specified for the 2010 and 2020 model years.
• The 2010 model year uses the 12961, while the surrounding years 2009 and 2011 both specify the 6411, indicating that the dome light socket configuration was not consistent across consecutive model years.
• The SV8.5 base designation on the 6411 refers to a single-contact festoon base with an 8.5mm contact cap width, a common standard in European and North American automotive interior lighting.
• The T10 designation on the 12961 describes the bulb's tubular envelope width of approximately 10mm, a widely used form factor in automotive parking, license plate, and interior lighting applications.
• Because the C63 AMG dome light socket type varies by model year, the correct bulb type is determined strictly by year rather than by shared electrical ratings.