Arduino Uno with MQ2 Gas Sensor Module: Monitoring Air Quality



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The MQ2 gas sensor module is a valuable tool for measuring various gases and air quality. In this guide, we’ll explore how to use an MQ2 sensor module with an Arduino Uno to detect and monitor the presence of gases in the environment.


image of mq2 sensor

The MQ2 gas sensor operates based on the principle of resistance change in response to the presence of different gases. It consists of a gas-sensitive material that alters its resistance when exposed to specific gases. The Arduino Uno reads this resistance, and through calibration, we can determine the type and concentration of gases present.

Components Required

To get started, gather the following components:

  1. Arduino Uno
  2. MQ2 Gas Sensor Module
  3. Jumper Wires
  4. Breadboard (optional)


Connect the MQ2 sensor module to the Arduino Uno as follows:

  1. Connect the module’s VCC pin to the 5V pin on the Arduino.
  2. Connect the module’s GND pin to any ground (GND) pin on the Arduino.
  3. Attach the module’s OUT pin to an analog pin on the Arduino, such as analog pin A0.


Here’s a basic Arduino code example to read gas concentrations from the MQ2 module and display them in the Serial Monitor:

const int mq2Pin = A0; // Define the analog pin connected to the MQ2 module

void setup() {



void loop() {

  int sensorValue = analogRead(mq2Pin); // Read the analog value from the MQ2 module

  float voltage = (sensorValue / 1024.0) * 5.0; // Convert the analog value to voltage

  Serial.print("Voltage: ");


  Serial.print("V | ");

  Serial.print("Gas Concentration: ");

  if (voltage < 1.0) {

    Serial.println("High Concentration");

  } else {

    Serial.println("Low Concentration");


  delay(1000); // Delay for 1 second before the next reading



Utilizing an MQ2 gas sensor module with an Arduino Uno empowers you to create projects that detect and monitor the presence of gases. Whether it’s for gas leak detection, indoor air quality assessment, or safety applications, the MQ2 module offers a reliable solution for gas sensing.


  1. What gases can the MQ2 sensor module detect?
  • The MQ2 module can detect a range of gases, including LPG, propane, methane, carbon monoxide, and hydrogen.
  1. Can I use the MQ2 sensor for outdoor air quality monitoring?
  • While the MQ2 is primarily designed for indoor use, it can provide useful information in controlled outdoor environments. However, it may not be suitable for extreme weather conditions.

Troubleshooting Q&A

  1. I’m getting inconsistent readings from the MQ2 module. What could be the issue?
  • Ensure that the sensor is adequately powered (5V) and that the connections are secure. Additionally, calibrate the sensor for optimal performance.
  1. The MQ2 sensor is not detecting any gases. How do I troubleshoot this?
  • First, confirm that the sensor is functioning correctly. Check for proper connections, and ensure that the gases you want to detect are present in the environment. Calibration may also be necessary for accurate readings.

By following this guide, you can effectively integrate the MQ2 gas sensor module with your Arduino Uno projects, enabling you to monitor air quality and detect the presence of gases for various applications. Whether you’re concerned about safety, environmental quality, or simply curious about the gases around you, the MQ2 module is a valuable asset.

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