A gauge having a housing, a light source disposed in the housing, a bezel, a display and a pointer. These vaccines demonstrate no undesirable side effects and protect against M. The conductor or conductors of the coil 16 is or are flowed through by current, in particular by direct current, and heated in this way. The circuit may inject current between the first lead electrode and the housing electrode, and measure a voltage potential, created by the current injection, between the second lead electrode and the housing electrode.