A protective tube device can protect a temperature sensor against contact with a fluid, and has a distal end containing the temperature sensor and has an outer wall provided for contact with the fluid, and a proximal end which is connected to the temperature sensor by electric lines and is intended for arrangement outside the fluid, wherein, on the outer wall of the distal end, an elastic membrane closes off a resultantly defined pressure transmission fluid reservoir in a fluid-impermeable manner, the pressure transmission fluid reservoir being connected fluidically by a fluid channel running within the protective tube device to a pressure sensor arranged in the proximal end.