3.15.1 Example:

In automotive applications, usually on one side is air i.e., pO₂ is 0.21 atm and the other side is at pO₂ of 10^-9 - 10^-21atm. . From the Nernst equation, one can calculate that at 350°C, a voltage difference, Δφ , between 0.25-0.6V will be developed which can be easily monitored and can be used as the feedback in control system to regulate the fuel supply to the engine.