A current controlled thin film resistor (varistor) has been fabricated using epitaxial YBa2Cu3O7-delta films deposited by high pressure oxygen sputtering. The I-V characteristics of the varistor have been studied and the corresponding resistance variation explained. The results of the studies carried out on varistors have been different width ratios at different temperatures are discussed in detail. A typical application of a varistor as a temperature sensor has been studied; its importance for low temperature measurement is discussed.