We would suggest checking the tyre pressures to ensure they are correct and resetting the system, before taking the car for a drive. If the tyre pressure warning activates again, stop as soon as possible and check the tyre pressures again to see if they have changed. If they are as before, or have increased as the tyres have warmed, this would suggest the fault is with the pressure monitoring system rather than the tyres themselves. It may just be a matter of having the sensors replaced, but we would suggest taking it to a local independent garage to have the system checked.