What is the low beam headlight bulb size for a 2018 Audi A4 Quattro?

The 2018 Audi A4 Quattro uses a HID-D5S LED bulb for the low beam headlights. We recommend upgrading to LED for better visibility.

What is the high beam headlight bulb size for a 2018 Audi A4 Quattro?

The high beam bulb size for the 2018 Audi A4 Quattro is HID-D5S LED.

Why are my 2018 Audi A4 Quattro headlights dim?

Dim headlights on a 2018 Audi A4 Quattro can be caused by aging halogen bulbs, which lose brightness over time, or oxidation (cloudiness) on the plastic headlight lenses. Upgrading to a HID-D5S LED LED conversion kit can provide a significantly brighter and whiter light output.

Which bulb fits the 2018 Audi A4 Quattro fog light?

The 2018 Audi A4 Quattro uses a LED Fog Light bulb for the fog light position.

Is the 2018 Audi A4 Quattro single or dual beam?

The 2018 Audi A4 Quattro uses a single bulb (dual filament) headlight system. This means one bulb controls both high and low beams.

Can I install LED bulbs on my 2018 Audi A4 Quattro?

Yes, the 2018 Audi A4 Quattro 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.

Does the 2018 Audi A4 Quattro have fog lights?

Yes, the 2018 Audi A4 Quattro takes a LED Fog Light bulb for the fog light position.

How do I change the headlight on a 2018 Audi A4 Quattro?

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.

Are LED headlights legal for a 2018 Audi A4 Quattro?

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.

How much does it cost to replace 2018 Audi A4 Quattro headlights?

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.

What is the difference between halogen and LED for a 2018 Audi A4 Quattro?

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.

This vehicle is part of the 2017–2019 Audi A4 Quattro generation. All models in this range share identical light bulb sizes.

Fitment Guaranteed for 2018 Audi A4 Quattro

What Size Bulbs Does a 2018 Audi A4 Quattro 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 A4 Quattro Have?

Owners of the 2018 Audi A4 Quattro will find a total of 10 lighting elements throughout the vehicle's exterior. It features a comprehensive lighting system powered by a halogen-based setup where a single HID-D5S LED dual-filament bulb handles both low and high beam duties within the same reflector. Note that Audi vehicles typically feature a CANbus electrical monitor that checks for specific bulb resistance.

LED Flicker Warning

This vehicle is known to use a CANbus system. Installing standard LEDs may cause flickering.

Use a CANbus decoder.

Can You Put LED Bulbs in a 2018 Audi A4 Quattro?

Upgrading to LED is one of the most effective ways to modernize your Audi's appearance and safety profile. Since your A4 Quattro uses a single HID-D5S LED bulb for both high and low beams, ensure your chosen LED kit is "dual-beam" compatible. This allows the LED circuitry to mimic the two-filament design of the original halogen bulb. Because Audi utilizes a CANbus system, standard LED bulbs may cause "bulb out" errors on your dashboard. Always opt for "Error-Free" or CANbus-ready kits which include the necessary resistors. Don't forget the LED Fog Light fog lights; switching these to LED can dramatically improve your visibility in adverse weather.

2018 Audi A4 Quattro Bulb Size Chart

Position	Bulb Size	Shop
Low Beam	HID-D5S LED	Buy HID-D5S LED →
High Beam	HID-D5S LED	Buy HID-D5S LED →
Fog Light	LED Fog Light	Buy LED Fog Light →
Brake Light	LED Bulb	Buy LED Bulb →
Side Marker	LED Bulb	Buy LED Bulb →
Turn Signal Front	12181NA	Buy 12181NA →
Parking Light	LED Bulb	Buy LED Bulb →
Turn Signal Rear	LED Bulb	Buy LED Bulb →
Reverse Light	LED Bulb	Buy LED Bulb →
Trunk Light	LED Light	Buy LED Light →