Changing bulbsChanging bulbs  - Changing bulbs for rear lights in side panel - Fuses and bulbs - Self-help - Audi A4 Owner's Manual - Audi A4

All bulbs can be changed easily after removing the rear light.

Rear light, mounting plate is highlighted

Rear light, mounting plate is highlighted

Ц Detach the bulb carrier.
Ц Renew the defective bulb (pull to remove from plug-in holder or turn to remove from bayonet holder).
Ц Attach the bulb carrier.
Ц Re-install the rear light.