Patent ID: 8257578
Filing Date: 2012-09-04
Classification: G01N

Abstract:
1. An anomaly diagnosing method for a gas sensor which diagnoses an anomaly thereof, the gas sensor comprising a gas sensor element which includes a solid electrolyte and electrodes for outputting a signal representing an electrical characteristic of the solid electrolyte; connection terminals which contact the electrodes so as to lead the signal outside the gas sensor; and a heater which heats the solid electrolyte, the method comprising: heating the solid electrolyte by use of the heater; outputting a detection signal for detecting an internal resistance of the gas sensor through the solid electrolyte and via the connection terminals and the electrodes, and measuring the internal resistance of the gas sensor on the basis of a response signal which is input via the connection terminals in response to the output of the detection signal; and obtaining, after the start of heating of the solid electrolyte by use of the heater, a first time required for the measured internal resistance to reach a first resistance and a second time required for the measured internal resistance to reach a second resistance different from the first resistance, and determining whether or not the gas sensor is anomalous by comparing a predetermined threshold value with a ratio of the first to second times.