MQ9 Carbon Monoxide Methane and LPG Gas Sensor Module 


MQ-9 Carbon Monoxide, Methane, and LPG Gas Sensor Module can be used to sense Carbon Monoxide and Methane Gas. The sensitive material of the MQ-9 gas sensor is SnO2, which with lower conductivity in clean air. It makes detection by method of cycling high and low temperature and detects CO when low temperature (heated by 1.5V). The sensor’s conductivity is higher along with the gas concentration rising. When the high temperature (heated by 5.0V), it detects Methane, Propane, etc. combustible gas and cleans the other gases adsorbed under low temperature


  • Good Sensitivity to CO/Combustible Gas
  • High Sensitivity to Methane, Propane, and CO
  • Long life and low cost
  • Simple Drive Circuit


Pin NamePin Description
VccThe [in is there to power the module, requires 5V
GroundTo connect the module to the system’s common ground
Digital OutDigital output pin, the Threshold value can be set by using the potentiometer
Analog OutAnalog output pin. Analog voltage based on the concentration of the gas 


Input voltageDC 5±0.2V
DO outputTTL digital 0 and 1 (0.1 and 5V)
AO output0.1-0.3V (relatively clean), the highest concentration voltage is about 4V
Dimensions32 x 20 x 22 mm (LxWxH)
Weight5 gm


  • Carbon monoxide (CO) and flammable gas detection: The MQ9 Gas Sensor is designed to detect both carbon monoxide and flammable gases such as methane, propane, and butane. It can be used in residential, commercial, or industrial settings to provide dual gas detection capabilities and enhance safety measures.
  • Indoor air quality monitoring: The module can be integrated into indoor air quality monitoring systems to measure carbon monoxide levels and detect flammable gases in enclosed spaces. It helps ensure a safe and healthy environment by alerting users to high levels of these gases, which can be emitted by faulty appliances or gas leaks.
  • Gas leakage detection in heating systems: The MQ9 sensor module is commonly utilized in heating systems, such as furnaces or boilers, to detect carbon monoxide and flammable gas leaks. It serves as an essential safety component, ensuring the early detection of gas leaks and preventing potential hazards associated with malfunctioning heating equipment.


Download the Datasheet of MQ9 Gas Sensor from the link given below.