2017 Audi A4 Bulb Size

Misconception: all headlight and signal bulbs look the same and swap in easily. It often seems true because bulbs share familiar shapes and fit into housings that look similar. That visual shortcut is a common trap. What is true is that a 2017 Audi A4 uses specific bulb types for different locations — low beam, high beam, fog, turn signals, and interior. Think of it as a parts map; the list on this page is a practical reference so you pick the right socket, lumen output, and legal type. A simple rule of thumb: match the vehicle year and function, not just the shape. Implications and quick recap: choosing correctly avoids glare, damage, or a failed inspection. Quick tests: compare part numbers, try the bulb in the socket before final assembly, and check fitment notes. Some links on this page are affiliate links; I may earn a small commission at no extra cost to you.