Hi all problem with tyre tpms have to reset warning on dash every second day since got car

last November had car in at Audi to check under warranty.Audi say could not find any fault and 

to take to tyre repairer and check wheels with water bath for slow puncture.No leaks found 

can’t tell what wheel seems to be a problem .Any advice 

               Thanks 

I'd be leaving the car with Audi for a few days for them to find the fault. Clearly one of the sensors has failed I suspect.

If you reported it originally when the car was under warranty and Audi haven't found fault or fixed it then you might still be covered. 

Cheers

Steve