Gas sensor

A gas sensor comprising:

• a measurement chamber into which exhaust gas is introduced;
• a reference gas chamber into which a reference gas is introduced;
• a first cell that includes a first electrode that is provided in the measurement chamber and a second electrode that is provided in the reference gas chamber, and removes oxygen that is contained in the exhaust gas that is introduced into the measurement chamber by a voltage being applied between the first electrode and the second electrode;
• a second cell that includes a third electrode that is provided in the measurement chamber and a fourth electrode that is provided in the reference gas chamber, in which a voltage is applied between the third electrode and the fourth electrode, and through which a second current flows which depends on a concentration of a specific gas component that is contained in the exhaust gas from which oxygen has been removed by the first cell;
• a third cell that that includes a fifth electrode that is provided in the measurement chamber and a sixth electrode that is provided in the reference gas chamber, through which a third current flows which depend on a concentration of residual oxygen that is contained in the exhaust gas from which oxygen has been removed by the first cell by a voltage being applied between the fifth electrode and the sixth electrode;
• and
• a control circuit, wherein the control circuit is configured to:
• detect a value of a first current that flows between the first electrode and the second electrode;
• detect a value of the second current;
• detect a value of the third current;
• calculate the concentration of the specific gas component based on a detected value of the second current detected by the control circuit and a detected value of the third current detected by the control circuit;
• determine whether a change has occurred in an oxygen concentration in the reference gas chamber based on a detected value of the first current detected by the control circuit;
• and
• correct at least either of the detected value of the second current or the detected value of the third current when the control circuit determines that a change has occurred in the oxygen concentration in the reference gas chamber.