Abstract: A temperature monitoring device containing a control system adapted to generate substantially periodic control waveforms applied to the control input of the light source with tunable wavelength connected to an optical fiber interferometer, in which a measuring optical fiber is connected in one its arms, and the interferometer output is connected to a detector whose output is connected to a signal processing module adapted to identify temperature changes in the optical fiber length function, in accordance with the invention, characterized in that the light source coherence length is longer than 0.5 m, and the period of the periodic waveform is shorter than or equal to 20 s, the difference between the minimum and maximum wavelength is higher than 3 ?m, and the optical fiber is adapted to its placement near exoenergetic devices in a vehicle, during its operation.