Cadillac ATS Headlight Bulb Size

The Cadillac ATS high beam and low beam headlight bulbs utilize a 9012 or D3S bulb size for optimal illumination. The replacement chart covers vehicle production years spanning 2013 to 2019 with corresponding bulb specifications.

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

High Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2013-2019	D3S (With HID Headlamps)	D3S	Check Price
2013-2019	9012 (With Halogen Capsule Headlamps)	HIR2	Check Price

Low Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2013-2019	D3S (With HID Headlamps)	D3S	Check Price
2013-2019	9012 (With Halogen Capsule Headlamps)	HIR2	Check Price

Bulb Specifications

Description	Type	Shop
ECE standard (Europe & worldwide). Mercury-free HID (xenon) discharge bulb with PK32d-5 base and integral ignitor, for projector-type housings. 42V, 35W.	D3S	Check Price
ANSI standard (US & Canada). Single-filament enhanced halogen bulb with PX22d base. 12V, 55W.	9012	Check Price

Other Locations

Additional Notes

The Cadillac ATS uses two distinct headlight bulb types across its 2013-2019 model years: the 9012 halogen bulb and the D3S HID bulb. The correct fitment depends entirely on which headlamp system the vehicle was built with, either halogen capsule headlamps or HID headlamps.
The 9012 is a single-filament halogen bulb rated at 12V and 55W, built to the ANSI standard used in the United States and Canada. It uses a PX22d base and serves as both the high beam and low beam bulb in halogen-equipped ATS models.
The D3S is a mercury-free HID xenon discharge bulb rated at 42V and 35W, conforming to the ECE standard used in Europe and worldwide. It features a PK32d-5 base with an integral ignitor and is designed specifically for projector-type housings.
Because the 9012 operates at 12V and the D3S operates at 42V, the two bulb types are electrically and physically incompatible. Each requires a different socket, wiring, and in the case of the D3S, a dedicated ballast system.
On the Cadillac ATS, the 9012 bulb performs dual duty, handling both high beam and low beam functions within the halogen headlamp system. This single-bulb-per-function design is characteristic of reflector or projector halogen housings that use one bulb to produce both beam patterns through a movable shield or separate optics.
The D3S similarly serves both high beam and low beam positions in HID-equipped ATS models, a configuration typical of bi-xenon projector housings where a single discharge bulb produces both beam patterns via a mechanical solenoid shield inside the projector.
The integral ignitor on the D3S bulb means the high-voltage starting component is built directly into the bulb body rather than housed separately in the vehicle. This design ties the ignitor replacement to the bulb replacement, distinguishing it from older HID bulb types that used external ignitors.
The 9012 bulb shares its physical envelope with the 9006 family but is not interchangeable with the 9006 or 9005 due to a different base configuration. The PX22d base on the 9012 is keyed to prevent installation of lower-rated bulbs in its socket.