Cadillac ATS 2018 Bulb Size
Bulb size chart
If you are looking up bulb sizes for a 2018 Cadillac ATS, this page is designed to help you verify the correct bulb by lighting position. That matters because the ATS can use different bulbs depending on the trim, lighting package, body style, and market, so the same car may not use the same setup in every spot.
Use this 2018 Cadillac ATS bulb guide to match each exterior and interior light location with the listed bulb type before you buy replacements. It covers common positions such as headlights, brake lights, turn signals, reverse lights, license plate lights, and cabin bulbs, making it easier to find the right fit the first time.
Fitment can vary on the 2018 Cadillac ATS, especially between halogen and HID headlight setups and between different trim or package combinations. Some bulbs are LED assemblies, while others use replaceable bulbs such as 921, 194, 7441, 7444NA, 2825/98, 7065, 194NA, or 9012 depending on position and configuration. If you are converting to aftermarket LED bulbs, check polarity, beam pattern, and error-free compatibility before ordering. The safest approach is to confirm the bulb already installed in your vehicle and compare it with the bulb chart on this page before purchase.
FAQ
What bulb does the 2018 Cadillac ATS use for the low beam and high beam with HID headlights?
For ATS models equipped with HID headlights, the listed headlight bulb for both high beam and low beam is D3S.
What bulb is used for halogen headlight versions of the 2018 Cadillac ATS?
For halogen headlight setups, the listed headlight bulb for both high beam and low beam is 9012.
What is the reverse light bulb size on a 2018 Cadillac ATS?
The back up reverse light bulb is 921.
What bulb fits the front turn signal on this model year?
The front turn signal light bulb is 7444NA.
What bulb is used for the front parking light on the 2018 Cadillac ATS?
The parking light bulb is 7444NA.
What bulb size is listed for the front side marker light?
The front side marker light bulb is 194NA.
What bulb size is listed for the rear side marker light?
The rear side marker light bulb is LED.
Are the brake lights and tail lights on the 2018 Cadillac ATS replaceable bulbs?
The brake light bulb and tail light bulb are listed as LED, so they are not standard replaceable incandescent bulbs in the way a 921 or 194 bulb would be.
What bulb does the center high mount stop light use?
The center high mount stop light bulb is listed as LED.
What bulb size is used for the license plate lights?
The license plate light bulb is listed as 2825 or 98.
What bulb fits the trunk or cargo area light?
The trunk or cargo area light uses 194 or 7441.
What bulb is used for the interior door lights and stepwell lights?
Both the interior door light and the stepwell light are listed as 194 or 7441.
What bulb size is used for the vanity mirror light?
The vanity mirror light bulb is 7065.
Does the 2018 Cadillac ATS use the same bulb sizes on every trim?
Not always. Trim level, lighting package, body style, and market can change the bulb setup, so it is best to verify the exact position on your vehicle before ordering.
Should I check the installed bulb before buying a replacement?
Yes. Checking the bulb already installed in your ATS is the best way to confirm fitment, especially if the car has been modified or if you are unsure whether it has halogen, HID, or LED equipment.