Exhaust sensor

An exhaust sensor detecting a concentration of a specific component in exhaust gas flowing through an exhaust passage of an internal combustion engine, comprising:

• a sensor cell having a solid electrolyte layer having an oxide ion conductivity, a first electrode arranged on one surface of the solid electrolyte layer so as to be exposed to the exhaust gas and comprised of a perovskite-type oxide, and a second electrode arranged on the other surface of the solid electrolyte layer so as to be exposed to a reference gas;
• a voltage application circuit applying voltage to the sensor cell so that a potential of the second electrode becomes higher than a potential of the first electrode,
• a current detection circuit detecting a current flowing through the sensor cell;
• and
• a concentration calculating part configured to calculate the concentration based on a current detected by the current detection circuit, wherein
• the current detection circuit detects a first current flowing through the sensor cell when fuel cut control where fuel stops being fed to combustion chambers of the internal combustion engine is being performed in the internal combustion engine and a predetermined voltage is applied from the voltage application circuit to the sensor cell, and detects a second current flowing through the sensor cell when normal control where fuel is being fed to the combustion chambers is being performed in the internal combustion engine and the predetermined voltage is applied from the voltage application circuit to the sensor cell, and
• the concentration calculating part is configured to calculate the concentration higher with respect to the second current when the first current is relatively low compared with when the first current is relatively high.