Template: MQ-135 Gas Sensor Arduino Guide

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The examples provided are based on the Arduino UNO, if you need to use other Arduino boards, please check if the board is compatible with the UNO.


Hardware connection

Hardware connection-Arduino
Connect to Arduino UNO
MQ135 Arduino Description
VCC 5V Power input
GND GND Ground
AOUT A0 Analog data output
DOUT D2 Digital data output


  • Please download and install Arduino IDE to your PC.
  • Download the demo codes, unzip and find the Arduino examples.
  • Open the Gas_Sensor.ino file by the Arduino IDE.
MQ5 Arduino 1.jpg
  • Build and upload the codes to the UNO board.
  • After downloading, you can run SSCOM to connect the MQ135 module so as to check the sensor.

MQ-5 Gas Sensor.00.jpg

Expected result

  • The sensor needs to preheat for about a minute to heat the internal sensitive materials of the sensor.
  • Put the sensor inside the device containing sensitive gas, and the indicator on the module lights up. The indicator goes off when the sensor is removed from the device.