A TPRD for a high pressure storage vessel including an integrated pressure sensor cooperative with an activation mechanism and a method of monitoring a TPRD for use in a fuel cell system. The TPRD comprises a release piston, moveable between an open and a closed position, which controls the flow of gas from a fuel storage vessel through a gas outlet port. The thermally activated activation mechanism comprises a gas-inlet chamber and a liquid-filled bulb having an air bubble. Upon activation, the release piston moves from the closed position to the open position. The integrated pressure sensor detects the pressure within the TPRD. A difference in pressure between that of the fluid within the fuel storage vessel and the pressure within the TPRD provides indicia of impaired movement of the release piston.