Interfacing MQ-135 Smoke Gas Sensor Module with Arduino

Table of Contents

MQ-135 Smoke Gas Sensor Module Features

MQ series sensor uses a small heater inside with an electrochemical sensor in order to measure different kinds of gas combinations. The MQ-135 sensor is a sensor for detecting air quality. This sensor is able to detect smoke, CO2, ammonia, alcohol and benzene in the air.


After turning on the module, wait for 2 minutes until the inside heater warms up.

You can download the datasheet of this module here.

MQ-135 Sensor Pinout

This sensor has 4 pins:

  • 5V: Module power supply – 5 V
  • GND: Ground
  • DOUT: Digital output
  • AOUT: Analog output

You can see pinout of this module in the image below.

Required Materials

Hardware Components

Arduino UNO R3 × 1
MQ-135 Air Quality Sensor Module × 1
Male to Female jumper wire × 1

Software Apps

Arduino IDE

Interfacing MQ-135 Sensor with Arduino

Step 1: Circuit

The following circuit shows how you should connect Arduino to MQ-135 module. Connect wires accordingly.

Step 2: Code

Upload the following code to your Arduino.
  modified on Sep 28, 2020
  Modified by MohammedDamirchi from Arduino Examples
*/ // the setup routine runs once when you press reset: void setup() { // initialize serial communication at 9600 bits per second: Serial.begin(9600); } // the loop routine runs over and over again forever: void loop() { // read the input on analog pin 0: int sensorValue = analogRead(A0); // print out the value you read: Serial.println(sensorValue); delay(20); }

After uploading the code, you can see the output in serial monitor.

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