What Size Bulbs Does a 2003 Audi A4 Use?
Correct headlight, fog light, and tail light bulb sizes. Sourced from OEM catalog data.
Installation Difficulty
Hard (Tight clearances)
Est. Replacement Cost
$50 - $150 (HID System)
What Lighting System Does the 2003 Audi A4 Have?
The 2003 Audi A4 features an extensive lighting system with 13 bulb positions. It uses factory HID/Xenon technology with D2S projector headlights. The A4 has been available from 1996 to 2019, and the 2003 model falls in the mid-generation years. As a Audi vehicle, it uses a CANbus electrical system that monitors bulb status.
LED Flicker Warning
This vehicle (Audi) is known to use a CANbus system that checks for burnt-out bulbs. Installing standard LEDs may cause them to flicker or trigger a dashboard error.
We highly recommend using a CANbus decoder or "Anti-Flicker" resistors.
Can You Put LED Bulbs in a 2003 Audi A4?
The 2003 Audi A4 comes equipped with factory D2S HID/Xenon headlights. These already produce significantly more light than halogen bulbs, so upgrading is generally unnecessary. When your HID bulbs burn out, replace them with OEM-spec D2S HID bulbs to maintain the correct color temperature and beam pattern. Avoid cheap aftermarket HID bulbs as they can produce incorrect beam patterns and blind oncoming drivers. Your fog lights use a H11 LED halogen bulb, which can be upgraded to LED for a whiter color match with your HID headlights.
How to Replace Bulbs on a 2003 Audi A4
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. HID headlights operate at high voltage. Always disconnect the battery before working on the headlight assembly. Never touch the HID ballast while the headlights are on, and handle the D2S capsule with gloves to avoid oil contamination. 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 H11 LED fog light socket.
Full Upgrade Bundle
Upgrade All 13 Positions at Once
2003 Audi A4 Complete Bulb Size Chart
| Position | Bulb Size | Shop |
|---|---|---|
Low Beam | HID-D2S LED | Buy HID-D2S LED |
High Beam | H9 LED | Buy H9 LED |
Fog Light | H11 LED | Buy H11 LED |
Brake Light | LED Bulb | Buy LED Bulb |
Dome Light | 6411 | Buy 6411 |
Side Marker | 5007 | Buy 5007 |
Turn Signal Front | 2827 | Buy 2827 |
License Plate | 6418 | Buy 6418 |
Map Light | 47830 | Buy 47830 |
Parking Light | 3457AK | Buy 3457AK |
Turn Signal Rear | 12496 | Buy 12496 |
Reverse Light | 7506 | Buy 7506 |
Trunk Light | 6418 | Buy 6418 |
Want to upgrade everything at once?
Shop Complete LED Kit for 2003 Audi A4How Long Do 2003 Audi A4 Headlight Bulbs Last?
HID/Xenon headlights on the 2003 Audi A4 typically last 2,000 to 3,000 hours, or about 4 to 6 years of regular driving. As HID bulbs age, they shift color toward pink or purple, which is a clear sign that replacement is needed. Flickering on startup also indicates a worn bulb or failing ballast. At 23 years old, the original bulbs on your A4 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 2003 Audi A4?
For the high beams, the H9 is interchangeable with H11, H8. 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.
2003 Audi A4 Headlight FAQ
Did Audi A4 Bulb Sizes Change Over the Years?
Over its production run from 1996 to 2019, the Audi A4 has seen bulb size changes in the Low Beam, High Beam and Fog Light positions. The 2003 model uses the earlier bulb specification that was in place before the change around 2017. Always verify the exact bulb size for your specific 2003 model year using the chart above, as using the wrong size can result in poor fitment or reduced light output.
Other A4 Years
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Other Vehicles That Use HID-D2S LED Bulbs
These vehicles from other makes also use a HID-D2S LED low beam bulb: