Using a novel approach, an oxygen sensor for monitoring high concentrations has been developed. The technique consists of applying a potential to an oxygen conducting solid electrolyte in one direction and the current measured, the potential reversed and the current re-measured, to obtain a current ratio which strongly and linearly depends on % oxygen in the high concentrations. Complications such as pinhole or porous diffusion barrier for limiting current are not required in this approach. Furthermore, by choosing appropriate values of the applied potential, it is possible to obtain extremely high sensitivity at any predetermined oxygen concentrations. Using this concept, it is possible to use a standard solid electrolyte oxygen sensor for application in automotive engines and other combustion systems.