I scanned a TT the other day with ESP and ABS lights on. There were no codes stored unfortunately.
I suggested that it could be the ABS sensor after some research. (Which it was)
Also, brake pedal sensor is has a similar effect apparently. I would check if the brake lights work to see if its that.
If not, as above, perhaps speed sensor. Its worth a scan to see if there are any codes. Are you anywhere near Kent, if so, I could
help?