Skip to main content
Fitment Guaranteed for 2018 Audi A3

What Size Bulbs Does a 2018 Audi A3 Use?

Correct headlight, fog light, and tail light bulb sizes. Sourced from OEM catalog data.

Installation Difficulty

Hard (Tight clearances)

Est. Replacement Cost

$15 - $40 (Halogen) / $30+ (LED)

What Lighting System Does the 2018 Audi A3 Have?

The 2018 Audi A3 features an extensive lighting system with 13 bulb positions. It uses halogen technology with a single HID-D5S LED dual-filament bulb handling both low and high beams. The A3 has been available from 2006 to 2019, and the 2018 model falls in the late-generation years. As a Audi vehicle, it uses a CANbus electrical system that monitors bulb status.

Can You Put LED Bulbs in a 2018 Audi A3?

Upgrading the 2018 Audi A3 to LED headlights is straightforward since it uses a single HID-D5S LED dual-filament bulb for both low and high beams. You only need one pair of LED bulbs to upgrade both functions. Look for a HID-D5S LED LED kit that specifically supports dual-filament operation to ensure both beams work correctly. Important: Audi vehicles use a CANbus system that detects bulb wattage. Standard LED bulbs may trigger dashboard warnings or flicker. Choose LED kits labeled "CANbus-compatible" or add inline decoder resistors to prevent these issues. For the fog lights, a H8 LED LED bulb provides a clean white output that pairs well with LED headlights.

How to Replace Bulbs on a 2018 Audi A3

To remove the headlight bulb, disconnect the wiring harness, then twist the bulb counter-clockwise and pull it straight out of the housing. Audi vehicles are known for tight engine bay clearances around the headlight assembly. You may need to remove the air intake duct, battery cover, or wheel well liner to access the bulbs. Budget 30 to 45 minutes per side for your first replacement. When installing the new bulb, avoid touching the glass with bare fingers. Skin oils create hot spots that shorten bulb life. Wear clean gloves or handle the bulb by its plastic base only. The fog lights are accessed from underneath the front bumper. You may need to remove a few plastic clips or screws from the fender liner to reach the H8 LED fog light socket.

Full Upgrade Bundle

Upgrade All 13 Positions at Once

Low Beam: HID-D5S LEDHigh Beam: HID-D5S LEDFog Light: H8 LEDBrake Light: High Mount Brake LightDome Light: 2825Side Marker: LED BulbsTurn Signal Front: 12181NALicense Plate: 2825Map Light: 2825Parking Light: LED BulbsTurn Signal Rear: LED BulbsReverse Light: LED BulbsTrunk Light: 2825
Shop Complete LED Kit

2018 Audi A3 Complete Bulb Size Chart

PositionBulb SizeShop
Low Beam
HID-D5S LEDBuy HID-D5S LED
High Beam
HID-D5S LEDBuy HID-D5S LED
Fog Light
H8 LEDBuy H8 LED
Brake Light
High Mount Brake LightBuy High Mount Brake Light
Dome Light
2825Buy 2825
Side Marker
LED BulbsBuy LED Bulbs
Turn Signal Front
12181NABuy 12181NA
License Plate
2825Buy 2825
Map Light
2825Buy 2825
Parking Light
LED BulbsBuy LED Bulbs
Turn Signal Rear
LED BulbsBuy LED Bulbs
Reverse Light
LED BulbsBuy LED Bulbs
Trunk Light
2825Buy 2825

Want to upgrade everything at once?

Shop Complete LED Kit for 2018 Audi A3
Installation Guide
Open in YouTube →
Video suggestion: Installation GuideBy YouTube

How Long Do 2018 Audi A3 Headlight Bulbs Last?

Standard halogen headlights on the 2018 Audi A3 have an expected lifespan of 500 to 1,000 hours, which works out to roughly 2 to 3 years of normal use. Signs of a failing halogen bulb include noticeably dimmer output, a yellowish tint compared to the other headlight, or intermittent flickering. At 8 years old, the original bulbs on your A3 are likely overdue for replacement. Even if they still illuminate, reduced brightness significantly impacts nighttime safety. When one headlight burns out, replace both sides at the same time. Bulbs from the same batch age at similar rates, and mismatched brightness is distracting to oncoming drivers.

What Bulbs Are Compatible with the 2018 Audi A3?

The D5S low beam bulb on the 2018 Audi A3 is a specific fitment. There are no widely recognized cross-compatible alternatives, so make sure to purchase the exact D5S size. Using the wrong bulb size can cause improper beam patterns that reduce your visibility and blind other drivers. It can also cause overheating inside the headlight housing, potentially warping the plastic lens or reflector. Always verify the bulb number before purchasing.

2018 Audi A3 Headlight FAQ

The 2018 Audi A3 uses a HID-D5S LED bulb for the low beam headlights. We recommend upgrading to LED for better visibility.

The high beam bulb size for the 2018 Audi A3 is HID-D5S LED.

The 2018 Audi A3 uses a single bulb (dual filament) headlight system. This means one bulb controls both high and low beams.

Yes, the 2018 Audi A3 comes with standard halogen bulbs from the factory, but they can be upgraded to LED. You will need a HID-D5S LED LED conversion kit for the low beams.

Yes, the 2018 Audi A3 takes a H8 LED bulb for the fog light position.

Turn off the vehicle and open the hood. Locate the headlight assembly from behind, remove the dust cover or retaining clip, disconnect the wiring harness, twist the old HID-D5S LED bulb counter-clockwise to remove it, then insert the new bulb and reassemble. Note: Audi vehicles use a CANbus system, so LED replacements may need an anti-flicker decoder. The whole process typically takes 10 to 30 minutes per side depending on accessibility.

LED bulbs used off-road or in auxiliary lights are legal everywhere. For on-road headlight use, legality varies by state. Many states allow LED retrofits as long as the beam pattern meets DOT standards. For the best legal compliance, choose a DOT-approved HID-D5S LED LED kit that is designed as a direct replacement and produces a proper cutoff pattern without excessive glare.

A pair of halogen HID-D5S LED bulbs costs $15 to $40, while LED conversion kits run $25 to $60 per pair. If you have a shop do the work, expect an additional $20 to $50 in labor per bulb. Replacing them yourself at home saves the labor cost and usually takes under 30 minutes.

Halogen bulbs produce a warm yellow light (around 3200K), last 500 to 1000 hours, and draw more power. LED bulbs emit a brighter white light (5000-6000K), last 25,000+ hours, and use less energy. LED upgrades for the HID-D5S LED position are available as direct plug-and-play replacements. Since the Audi uses CANbus monitoring, choose a CANbus-compatible LED kit to avoid dashboard errors.

Did Audi A3 Bulb Sizes Change Over the Years?

Over its production run from 2006 to 2019, the Audi A3 has seen bulb size changes in the Low Beam, High Beam and Fog Light positions. The 2018 model uses the newer bulb specification introduced around 2017. Always verify the exact bulb size for your specific 2018 model year using the chart above, as using the wrong size can result in poor fitment or reduced light output.

Other A3 Years

20192017201620152012201120102009200820072006
1008090A4A4 AllroadA4 QuattroA5A5 Quattro

Other Vehicles That Use HID-D5S LED Bulbs

These vehicles from other makes also use a HID-D5S LED low beam bulb:

2019 Alfa Romeo 4C2019 Alfa Romeo Giulia2019 GMC Sierra 1500 Limited2019 GMC Sierra 25002019 GMC Terrain2018 Chevrolet Silverado