Cadillac CTS License Plate Bulb Size

The Cadillac CTS license plate light requires a 12961 bulb size for proper installation and function within the rear exterior lighting assembly. Available data covers the span from 2003 through 2019 for the specified vehicle and component.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2016-2019	12961
2003-2013	12961

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961

Other Locations

Additional Notes

The Cadillac CTS uses the 12961 bulb for the license plate position across all specified model years from 2003-2019.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor.
T10 refers to the bulb's tubular shape, with the number indicating a width of 10 millimeters.
The 12961 operates on 12 volts at 5 watts, which is standard for low-current auxiliary lighting positions such as license plate illumination.
The base type is W2.1x9.5d, a wedge-style base that relies on tension from the socket rather than a bayonet or screw mechanism to maintain contact.
The W2.1x9.5d base specification defines the exact contact width and insertion depth, meaning only bulbs sharing this base type are physically compatible with the socket.
Because the 12961 is a Philips-specific part number, equivalent bulbs from other manufacturers must match the T10 form factor, W2.1x9.5d base, 12V rating, and 5W output to serve as direct replacements.