For the 2000 Audi TT, low-beam fitment depends on the headlight equipment: halogen headlights use an H1 bulb, while HID headlights use a D2S bulb. The supplied fitment data does not list a separate high-beam bulb, so verify the headlamp assembly before ordering or replacing a high-beam lamp.
Front fog lights may use either H3 or H3C, making the fog-lamp housing an important compatibility check. Other notable exterior applications include 64136 for the front turn signal, 7506 for the rear turn signal and reverse light, and 7528 for the brake and tail lights. The center stop lamp is listed as LED.
Interior and body lighting also includes 6418 for the license plate and courtesy lights, 64132 for the parking and front side-marker lights, and either 2825 or 98 for the rear side marker and trunk light. Dome-light fitment is listed as either 6411 or 6428.