Patent ID: 8736274

Claim:
A method for diagnosing an electrochemical sensor comprising a sensor unit including a solid or liquid electrolyte between a sensing electrode with which a gas to be detected makes contact and an opposite electrode, wherein the concentration of the gas to be detected is detected on the basis of a current flowing between the sensing electrode and the opposite electrode, or a voltage corresponding to the current, and wherein a water tank is connected to a lower part of the sensor unit for accommodating water or an absorbent polymer that has been caused to absorb water in an inner space thereof, the water present in the inner space being supplied to the electrolyte in the sensor unit, the method comprising the step of: diagnosing whether or not the electrochemical sensor is in an error state representing a process of moving from a desiccated state in which there is no water at all in the water tank and there is not enough moisture in the electrolyte, to a completely dry state in which there is no moisture at all in the electrolyte when a resistance of the electrolyte is increased.