The Audi A4 is an easy vehicle to maintain, and upkeep is generally hassle-free. Changing an Audi A4's headlight is a fairly simple process.
Place a piece of cardboard between the headlight and the bumper to protect your vehicle from getting scratched when you remove the headlight. Use masking tape to hold the cardboard in place.
Remove the four screws that hold the headlight to the vehicle's frame. Pull the headlight away from the vehicle's frame so you have access to the back of the headlight.
Locate the electrical connector block on the back of the headlight. Squeeze the sides of the block and pull it away from the headlight to access the bulb.
Remove the bulb from the headlight. Push the bulb in, toward the connector block, and turn it until it releases. Push the new bulb into the block and turn it until it locks in place.
Plug the electrical connector block back into the headlight and place the headlight back into the vehicle's frame. Secure the headlight with the screws. Remove the cardboard from the vehicle bumper.
Use a clean, dry cloth to handle the new bulb and put in the electrical connector block. The oil from your hands can cause the bulb to burn out quicker.