How to Change the Battery on an Audi A4

1. Pop the hood and pull away the rubber molding that sits at the firewall near the cowl using your hands. Then pull away the tray located there to expose most of the battery.
2. Unbolt the passenger side of the wiper cowl using a 3/8-inch ratchet and socket, as well as a Phillips-head screwdriver. Once you've disconnected the hardware, pull the cowl away from the vehicle to expose the rest of the battery.
3. Disconnect the negative terminal from the battery using an open-end wrench, then repeat the process for the positive terminal. Unbolt the battery tie-down from the car using a 3/8-inch ratchet and socket. Once it's disconnected, pull the battery out of the cowl and place it to the side.
4. Place the replacement battery in the cowl, and reconnect the battery terminals using an open-end wrench, connecting first the positive terminal, then the negative. Then reinstall the battery tie-down using the 3/8-inch ratchet and socket.
5. Reinstall the passenger side windshield cowl using the Phillips-head screwdriver and the 3/8-inch ratchet and socket, Slide the plastic battery cover onto the firewall, and then reinstall the rubber molding by pushing it in place.