A sensor and transmitter is employed with a pressurized chamber of a downhole tool to be able to tell at a glance when the tool is delivered for service that it is properly charged. The sensor and transmitter can be integrated within the tool so as to be protected from damage during run in. While in service the sensor and transmitter can monitor pressure in real time and include a capability to send surface signals for real time monitoring of chamber pressures corrected for the service depth, temperature and density of the hydraulic fluid, for example. The signal can be acoustic through the control line or the annulus or delivered through a fiber optic cable or signal wire run in the hydraulic control line, an auxiliary line or through the annulus.