It could be the indercator switch i just had the same fault on a Hyundai and it was the indercator switch
It's built into the hazard light switch. The hazard light button will slide out, with the relay (small box) attached.
It contains two relays, one for hazard lights and the other for turn signals. The one for the turn signals is defective and must be replaced.
Dealer's parts department.
The hazard rely may need replacing. Look under hood close to battery, remove old relay switch and replace with new.
It's in the hazard warning switch. You need to replace the switch.
Warning light symbols with explanations for 2003 Audi a4
The turn indicator relay in an Audi TT is integrated with the hazard switch. To replace the relay you would need to replace the hazard switch.
Behind the hazard button
The turn and hazard flasher relays are incorporated into hazard switch.
behind the hazard button, its built as complete assembly for Turn/hazard signal
warning lights
Inside the hazard switch.