Cadillac STS Dome Light Bulb Size

The Cadillac STS dome light requires bulb size PC168 or 212-2 depending on the specific version of the vehicle. Data for the bulb sizes covers the range from 2005 to 2011.

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
2010-2011	PC168
2005	212-2

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10) with printed circuit board twist-lock socket, for instrument clusters. 12V.	PC168
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	212-2

Other Locations

Additional Notes

The PC168 is a miniature wedge bulb in the T10 form factor, fitted with a printed circuit board twist-lock socket rather than a standard wedge base. This socket type is designed specifically for instrument cluster applications and is not interchangeable with conventional T10 wedge sockets despite sharing the same bulb body size.
The Cadillac STS uses the PC168 for the dome light position in the 2010-2011 model years. This bulb operates at 12V and conforms to ANSI standards recognized in both the United States and Canada.
The 212-2 is a festoon-type bulb with an SV8.5 base and a 41mm length. It operates at 12V with a power rating of 12W, and it also conforms to ANSI standards for the US and Canadian markets.
The 2005 Cadillac STS dome light position uses the 212-2 festoon bulb. The festoon format is physically distinct from the T10 wedge format used in the 2010-2011 model years, meaning the two bulb types are not interchangeable across these model years.
The SV8.5 base on the 212-2 refers to a cylindrical festoon cap held in place by spring-loaded contacts at each end of the housing, a mounting method that differs fundamentally from the twist-lock socket required by the PC168.