Gas sensor

A gas sensor comprising:

• a first sensor part configured to output a first detection signal according to a concentration of a target gas;
• a second sensor part configured to output a second detection signal according to the concentration of the target gas;
• and
• a signal processing circuit configured to control the first and second sensor parts and calculate the concentration of the target gas based on the first and second detection signals,
• wherein the signal processing circuit is configured to:
• control the first sensor part to repeatedly perform a first gas concentration measurement operation to acquire the first detection signal;
• control the second sensor part to start and repeatedly perform a second gas concentration measurement operation to acquire the second detection signal in response to a gas concentration calculated from the first detection signal reaching or exceeding a first threshold value;
• and
• stop the second gas concentration measurement operation in response to at least one of the gas concentration calculated from the first detection signal and the gas concentration calculated from at least the second detection signal reaching or falling below a second threshold value, and
• wherein an execution frequency per unit time of the second gas concentration measurement operation from its start to its stop is higher than an execution frequency per unit time of the first gas concentration measurement operation during a period in which the first gas concentration measurement operation is repeatedly performed.