A method for detecting at least one gas quantity of at least one predetermined gas from a sensor for measuring a plurality of gases, said sensor comprising a sensitive layer configured to measure the plurality of gases having an impedance Zs and a heating layer on which the sensitive layer is mounted, said heating layer being configured to be supplied with electrical energy in order to vary the temperature of the sensitive layer, said method comprising: - a step of supplying the heating layer with at least a first increasing voltage ramp defining a linear change of the supply voltage, then with a second decreasing voltage ramp defining a linear change of the supply voltage between a low voltage value and a high voltage value, in order to modify the temperature of the sensitive layer during a variation period according to a temperature ramp comprising an increasing part and a decreasing part, - a step for determining the temperature Ts of the sensitive layer from a determined thermal resistance Rth, the power P generated by the heating layer and a measurement of the ambient temperature Ta according to the following formula: Ts = P * R th + T A - a step of measuring variations in the impedance Zs of the sensitive layer at several temperatures of the sensitive layer during the variation period, so as to detect a plurality of gas quantities, - a detection step for detecting: - a first non-linear variation of the impedance Zs of the sensitive layer at a given temperature range ΔT of the sensitive layer during the first ramp-up and - a second non-linear variation of the impedance Zs of the sensitive layer measured at the same given temperature range ΔT of the sensitive layer during the second decreasing ramp, - a step of comparing the first variation of the impedance Zs and the second variation of the impedance Zs with a database associating a predetermined gas with a temperature range of the sensitive layer, with a rising variation in impedance Zs and with a falling variation of the impedance Zs, the temperature ranges each corresponding to a gas to be measured, - the step of comparing being implemented by comparing the first variation and second non-linear variation of the impedance Zs measured with the upward and downward variations stored in the database by correspondence of variation form and temperature range, in order to associate the quantity of gas measured with a predetermined gas. - a step of supplying the heating layer with at least a first increasing voltage ramp defining a linear change of the supply voltage, then with a second decreasing voltage ramp defining a linear change of the supply voltage between a low voltage value and a high voltage value, in order to modify the temperature of the sensitive layer during a variation period according to a temperature ramp comprising an increasing part and a decreasing part, - a step for determining the temperature Ts of the sensitive layer from a determined thermal resistance Rth, the power P generated by the heating layer and a measurement of the ambient temperature Ta according to the following formula: Ts = P * R th + T A - a step of measuring variations in the impedance Zs of the sensitive layer at several temperatures of the sensitive layer during the variation period, so as to detect a plurality of gas quantities, - a detection step for detecting: - a first non-linear variation of the impedance Zs of the sensitive layer at a given temperature range ΔT of the sensitive layer during the first ramp-up and - a second non-linear variation of the impedance Zs of the sensitive layer measured at the same given temperature range ΔT of the sensitive layer during the second decreasing ramp, - a first non-linear variation of the impedance Zs of the sensitive layer at a given temperature range ΔT of the sensitive layer during the first ramp-up and - a second non-linear variation of the impedance Zs of the sensitive layer measured at the same given temperature range ΔT of the sensitive layer during the second decreasing ramp, - a step of comparing the first variation of the impedance Zs and the second variation of the impedance Zs with a database associating a predetermined gas with a temperature range of the sensitive layer, with a rising variation in impedance Zs and with a falling variation of the impedance Zs, the temperature ranges each corresponding to a gas to be measured, - the step of comparing being implemented by comparing the first variation and second non-linear variation of the impedance Zs measured with the upward and downward variations stored in the database by correspondence of variation form and temperature range, in order to associate the quantity of gas measured with a predetermined gas.