I have A3 TDI. Ive had a problem over the last few weeks, the car overboosts and then turns itself into 'get home' mode. Ive had a guy come out and plug it in. He's saying that the car is overboosting if you turn the car off and on it cures the problem, hes says the turbo is working fine just somethings telling the car to overboost, hes told me the only fix he knows off is a new turbo?????