If a vacuum has been pulled on a system and there is a leak, the gauge will read higher than the actual pressure in the system. This is because the leak will allow air to enter the system, which will increase the pressure. The amount that the gauge reads higher than the actual pressure will depend on the size of the leak. If the leak is small, the gauge may only read slightly higher than the actual pressure. However, if the leak is large, the gauge may read much higher than the actual pressure.