Reset service light indicator, engine oil life Audi TT, oil reset instructions:

For Fixed Interval servicing, you can use the following procedure:
Start with the key in, but the ignition turned OFF
Press and hold the button on the right of the display, while turning the ignition one click (to position 1)
Release the button on the right
“SERVICE” should now appear on the display
Press and hold the button on the left of the display until it shows “SERVICE IN xxxx Miles / Kilometres”
Release the left button, then turn off the ignition