Audi A4 & A3 LED Interior Lights — Bulb Sizes & CANBUS Guide
Audi interiors are clean and modern, which is exactly why the yellow halogen bulbs in them stand out so much. Swapping to LED is the fastest way to make an A4 or A3 interior match how good the rest of the car already looks.
This guide covers the A4 (B8, B9) and A3 (8P, 8V), including the bulb sizes and the CANBUS fix that Audi owners need to know about.
Audi A4 and A3 bulb sizes
| Position | A4 B8/B9 | A3 8P/8V |
|---|---|---|
| Dome light | 42mm festoon | 42mm festoon |
| Map / reading lights | T10 (W5W) | T10 (W5W) |
| Footwell lights | T10 (W5W) | T10 (W5W) |
| Glovebox light | T10 or festoon | T10 (W5W) |
| Door puddle lights | T10 (W5W) | T10 (W5W) |
| Trunk light | Festoon | T10 (W5W) |
Audi changed bulbs across trims and years, so check your specific model. The door puddle lights especially vary between standard and higher-spec trims.
The Audi CANBUS problem (and the fix)
Audi's bulb monitoring is relentless. Of all the German brands, Audi is up there with the most sensitive systems. Put a standard LED in the map lights and the A4 B8 will flag a bulb-out warning in the cluster, even though the light is working fine.
The fix is the same as always: error-free CANBUS bulbs. They have a resistor built in that mimics a halogen, so the monitoring system stays quiet. Do not cheap out here. The extra couple of dollars is worth not staring at a warning every time you drive.
The door puddle light rabbit hole
Once you do the footwells, you will notice the door puddle lights are still halogen, and it will bother you. Audi made those easy to do too. They use the same T10 bulbs on most trims, and the housing pops out with a small trim tool.
Plan the whole job at once. Do the dome, map, footwells, puddle lights, and trunk together so you are not taking trim panels off twice.
Installation notes
- Pop the lens covers off with a plastic trim tool. Audi clips are firm, so use steady pressure, not force.
- Remove the old bulbs. Pull straight out.
- Insert the LEDs. Plug and play.
- Test each one. Audi map light sockets are small and easy to install backwards. If a bulb doesn't light, flip it 180 degrees before assuming it is dead.
- Close everything up.
What color temperature suits an Audi?
6000K if you have the LED daytime running lights. It ties the whole look together. If your A4 or A3 is an older halogen-DRL model, 5000K blends better and looks less blue.
Frequently asked questions
Will swapping interior bulbs void my Audi warranty? No. Interior bulb changes are cosmetic and do not affect the electrical or drivetrain warranty.
Why do my Audi LEDs flicker on startup? Audi pulses voltage to check for burnt-out bulbs on some circuits. Error-free CANBUS bulbs handle that pulse without flickering.
Do I need VCDS or any coding? For interior lights, no. It is a straight bulb swap with error-free bulbs.
The bottom line
The A4 and A3 reward the effort more than almost any other car. The interior is already good, and LED lighting makes it look like a much newer model. Just use error-free bulbs and do the whole interior at once.
Browse custom-fit LED interior kits for Audi →
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