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MQ-2 Gas Sensor with Arduino UNO

MQ-2 Gas Sensor with Arduino UNO
Atribot team

Written by

Atribot team

Last updated

June 18, 2026

Introduction

The MQ-2 Gas Sensor is a commonly used sensor for detecting gases such as LPG, propane, methane, hydrogen, and smoke. It is widely used in gas leakage detection systems, fire safety devices, air quality monitoring projects, and industrial safety applications.

In this tutorial, you will learn how to interface the MQ-2 Gas Sensor with an Arduino UNO, upload the code, and monitor gas concentration levels using the Serial Monitor. By the end of this guide, you'll understand how to detect the presence of combustible gases and smoke in your Arduino projects.

Components Required

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Item NameQtyAction
Arduino UNO
1
MQ-2 Gas Sensor
1
USB Cable
1
Breadboard
1
Jumper Wires
1

Tools Required

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Item NameAction
Soldering Iron
Screwdriver

Software Required

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Item NameAction
Arduio IDE

Circuit Diagram

MQ-2 Gas Sensor with Arduino UNO
MQ-2 Gas Sensor with Arduino UNO

Source Code

MQ-2_Gas_Sensor_with_Arduino_UNO.inocpp
const int gasSensorPin = A0;

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  int gasValue = analogRead(gasSensorPin);

  Serial.print("Gas Sensor Value: ");
  Serial.println(gasValue);

  delay(1000);
}

Step by Step Instructions

Step 1: Connect the MQ-2 Sensor

Make the following connections:

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MQ-2 Gas Sensor

Arduino UNO

VCC

5V

GND

GND

AOUT

A0

Step 2: Open Arduino IDE

  1. Launch Arduino IDE.

  2. Connect Arduino UNO using USB.

  3. Select:

    • Board → Arduino UNO

    • Port → Correct COM Port

Step 3: Create a New Sketch

Create a new Arduino sketch and paste the provided code.

Step 4: Verify the Code

Click the Verify button to check for syntax errors.

Step 5: Upload the Code

Click Upload and wait until the upload process completes successfully.

Step 6: Open Serial Monitor

  1. Open Serial Monitor.

  2. Set the baud rate to 9600.

  3. Allow the MQ-2 sensor to warm up for about 20–30 seconds.

  4. Bring a gas source or smoke near the sensor (carefully and safely).

The Serial Monitor will display changing sensor values based on the detected gas concentration.

Expected Output

Gas Sensor Value: 120
Gas Sensor Value: 135
Gas Sensor Value: 128

When gas or smoke is detected:

Gas Sensor Value: 450
Gas Sensor Value: 620
Gas Sensor Value: 780

Conclusion

In this tutorial, you learned how to interface the MQ-2 Gas Sensor with Arduino UNO and monitor gas concentration levels using analog readings. This setup can be used in gas leakage detection systems, smoke detectors, safety monitoring devices, and various environmental monitoring applications.