A method, comprising: - driving (1002, 1050) a heated metal oxide semiconductor gas sensor by supplying to the sensor a first heating power value, - receiving from the sensor a sensing signal indicative of a sensed entity, - detecting (1004, 1056), as a function of the sensing signal from the sensor, onset of a sensor contamination condition, - if said detecting fails to indicate onset of a sensor contamination condition (1004, N; 1056, N), continuing supplying (1002, 1050) to the sensor said first heating power value, - if said detecting indicates onset of a sensor contamination condition (1004, Y; 1056, Y), activating (1006, 1072) a protection mode, the protection mode comprising supplying to the sensor a second heating power value for a protection interval, said second heating power value lower than said first heating power value, wherein the signal from the sensor is indicative of a resistance value of the sensor and said driving (1002, 1050) the sensor by supplying to the sensor the first heating power value comprises intermittently supplying to the sensor the first heating power value for a plurality of time intervals, wherein detecting (1004, 1056) onset of a sensor contamination condition comprises: - sensing, as a function of the sensing signal from the sensor, a plurality of resistance values of the sensing signal at the ends of the time intervals in said plurality of time intervals, - calculating, as a function of the sensing signal from the sensor, a plurality of slope values indicative of the behavior of the sensing signal over the time intervals in said plurality of time intervals, - checking (1004, 1056) said resistance values and said slope values against a reference template, and - declaring onset of a contamination condition if said resistance values and said slope values fail to comply with said reference template, characterised in that the method further comprises: - generating a plot of said slope values against said resistance values, wherein said plot is aligned with an alignment direction, - checking whether said alignment direction matches with a reference alignment direction, and - declaring onset of a contamination condition if said alignment direction fails to match with said reference alignment direction. - driving (1002, 1050) a heated metal oxide semiconductor gas sensor by supplying to the sensor a first heating power value, - receiving from the sensor a sensing signal indicative of a sensed entity, - detecting (1004, 1056), as a function of the sensing signal from the sensor, onset of a sensor contamination condition, - if said detecting fails to indicate onset of a sensor contamination condition (1004, N; 1056, N), continuing supplying (1002, 1050) to the sensor said first heating power value, - if said detecting indicates onset of a sensor contamination condition (1004, Y; 1056, Y), activating (1006, 1072) a protection mode, the protection mode comprising supplying to the sensor a second heating power value for a protection interval, said second heating power value lower than said first heating power value, wherein the signal from the sensor is indicative of a resistance value of the sensor and said driving (1002, 1050) the sensor by supplying to the sensor the first heating power value comprises intermittently supplying to the sensor the first heating power value for a plurality of time intervals, wherein detecting (1004, 1056) onset of a sensor contamination condition comprises: - sensing, as a function of the sensing signal from the sensor, a plurality of resistance values of the sensing signal at the ends of the time intervals in said plurality of time intervals, - calculating, as a function of the sensing signal from the sensor, a plurality of slope values indicative of the behavior of the sensing signal over the time intervals in said plurality of time intervals, - checking (1004, 1056) said resistance values and said slope values against a reference template, and - declaring onset of a contamination condition if said resistance values and said slope values fail to comply with said reference template, - sensing, as a function of the sensing signal from the sensor, a plurality of resistance values of the sensing signal at the ends of the time intervals in said plurality of time intervals, - calculating, as a function of the sensing signal from the sensor, a plurality of slope values indicative of the behavior of the sensing signal over the time intervals in said plurality of time intervals, - checking (1004, 1056) said resistance values and said slope values against a reference template, and - declaring onset of a contamination condition if said resistance values and said slope values fail to comply with said reference template, characterised in that the method further comprises: - generating a plot of said slope values against said resistance values, wherein said plot is aligned with an alignment direction, - checking whether said alignment direction matches with a reference alignment direction, and - declaring onset of a contamination condition if said alignment direction fails to match with said reference alignment direction. - generating a plot of said slope values against said resistance values, wherein said plot is aligned with an alignment direction, - checking whether said alignment direction matches with a reference alignment direction, and - declaring onset of a contamination condition if said alignment direction fails to match with said reference alignment direction.