Preparation
 

• Make sure your car is parked on a flat surface, the engine is turned off, and the keys are removed from the ignition to prevent any accidental movements.
• Allow the headlights to cool down if they have been in use, as they can become very hot.
• Gather necessary tools such as a screwdriver and, if needed, the new headlight bulb. Ensure the replacement bulb matches the specifications outlined in the vehicle’s owner manual.

 
Locate the Headlight Assembly
 

• Open the hood of your Audi A4 by pulling the hood release lever located inside your vehicle.
• Secure the hood with the prop rod if it's not equipped with a hydraulic hood lift.
• Allow yourself adequate lighting to see inside the engine compartment.

 
Access the Headlight Bulb
 

• Identify the rear of the headlight assembly unit where you need to replace the bulb.
• Depending on the configuration of your Audi A4, you may need to remove the air intake duct or other components to gain clear access to the headlight cover. Be sure to keep track of any screws or clips that you remove.
• Locate the plastic or rubber dust cover behind the headlight and remove it by turning it counterclockwise or by gently prying it off, if necessary.

 
Remove the Old Bulb
 

• Directly behind the cover, you will find the bulb holder, which is typically secured by a metal clip or turning mechanism.
• Gently release the clip or turn the bulb holder to detach it from the assembly.
• Pull the old bulb straight out from the socket. Avoid excessive force as this might damage connections.

 
Install the New Bulb
 

• Without touching the glass (to prevent oils from your hands causing damage when the bulb heats up), insert the new bulb into the socket.
• Ensure it sits firmly in place and that the correct bulb is aligned properly with the assembly fittings.
• Secure the bulb with the metal clip or turning mechanism.

 
Reassemble the Headlight Assembly
 

• Replace the dust cover by securing it in place with a clockwise twist or snapping it back onto its housing.
• If you had to remove any components like the air intake duct, reattach them carefully, making sure all screws and clips are secured tightly.

 
Test the New Bulb
 

• Close the hood and get into the driver’s seat.
• Turn on the ignition and headlights to check if the new bulb is working correctly.
• Aim the headlights against a flat surface like a garage door or a wall to ensure proper alignment.

 
Final Steps
 

• Dispose of the old bulb responsibly. Many auto parts stores offer recycling services for used bulbs.
• If the new bulb does not work, double-check all connections and consider consulting your Audi’s manual for further troubleshooting steps or professional assistance.
• Ensure all tools are properly stored and your workspace is clean.