Fuel Pressure Release
WARNING: This page is about a different car, the 1995 Audi A6. However, it is still accessible from the selected car via links, so may be relevant.
Remove fuel pump relay. See ELECTRICAL COMPONENT LOCATIONS at beginning of article. Start engine. Allow engine to run until it stops. Turn ignition off. Disconnect negative battery cable. Slight pressure may remain in system. Before disconnecting any fuel system line, cover connector with a clean shop towel. Install fuel pump relay.