Patent ID: 7338592

Claim:
A method for evacuating and detecting leaks in a sealed internal reference chamber of a solid electrolyte oxygen sensor, having an internal electrode and an external electrode, said method comprising: a. applying a first direct current (DC) pumping current to the internal and external electrodes to evacuate the reference chamber while measuring a sensor voltage and while measuring an elapsed time from the application of said DC pumping current; b. comparing the measured sensor voltage and the measured elapsed time to a predetermined sensor voltage limit and a first predetermined elapse time limit respectively to ascertain the presence of a leak in said reference chamber; c. progressively reducing the DC pumping current applied to the sensor electrodes to continue the evacuation of the reference chamber, and d. while reducing the current, comparing the reduced DC pumping current to a predetermined current limit and comparing the elapsed time to a second predetermined time limit to detect a leakage in the chamber.