Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	MQ-135
Detection Gases	Ammonia, NOx, Alcohol, Benzene, Smoke, CO2
Operating Voltage	5V DC
Output Signal	Digital Switch Output (0 and 1) & Analog Voltage Output
Preheat Time	24-48 Hours
Interface Type	4-Pin Header (VCC, GND, DO, AO)
PCB Dimensions	32mm x 20mm x 15mm
Adjustable Sensitivity	Yes, via Onboard Potentiometer
Compatibility	Arduino, Raspberry Pi, ESP8266, ESP32
Package Contents	1x MQ-135 Sensor Module

6 reviews

Anonymous

Mar 30, 2026

Rating: 5/5

Works great with ESP32

Integrated this into my smart home system using an ESP32. The voltage levels match perfectly without needing extra logic shifters. It successfully triggers alerts when cooking fumes get too strong.

Anonymous

Mar 22, 2026

Rating: 5/5

Excellent value for money

Bought this for a university project on indoor pollution. The digital output threshold is easy to adjust with the potentiometer. Documentation online is plentiful, making integration simple even for beginners.

Anonymous

Mar 15, 2026

Rating: 5/5

Perfect for my home air monitor project

This sensor works exactly as described. I connected it to an Arduino Uno and had readings within minutes after the initial preheat. The analog output is smooth and responds well to changes in air quality when testing with safe household items like rubbing alcohol.

Anonymous

Mar 08, 2026

Rating: 3/5

Good sensor, instructions could be better

The hardware itself is high quality and sensitive. However, the included paper manual is very basic. You will need to look up datasheets and tutorials online to understand the pinout and calibration process fully.

Anonymous

Mar 03, 2026

Rating: 4/5

Good sensitivity, needs calibration time

Great module for monitoring greenhouse conditions. Just remember that it needs a long preheat time (about 24 hours) before the readings stabilize. Once warmed up, it detects ammonia and other gases very reliably.

Anonymous

Mar 02, 2026

Rating: 4/5

Solid performance for prototyping

We use these in our makerspace for various workshops. They are robust and handle student handling well. The only downside is the power consumption is slightly higher than expected, but acceptable for benchtop prototypes.

5 FAQ

Q: What is the warm-up time required before accurate reading?

A: For stable and accurate readings, we recommend powering the sensor for at least 24 to 48 hours initially. After the first cycle, it stabilizes faster upon subsequent uses.

Q: Is the output voltage 3.3V or 5V compatible?

A: The module operates on 5V. The analog output ranges from 0V to 5V. If connecting to a 3.3V microcontroller like an ESP8266, please use a voltage divider on the analog pin to prevent damage.

Q: Can I use this outdoors in the rain?

A: No, this module is not waterproof. It should only be used in dry, indoor environments or housed within a weatherproof enclosure with proper ventilation if used outside.

Q: Does this module come with headers soldered?

A: Yes, the 4-pin header comes pre-soldered to the board, ready for immediate use with jumper wires or breadboards.

Q: Can this detect carbon monoxide specifically?

A: The MQ-135 is sensitive to a broad range of harmful gases including CO, ammonia, and benzene. While it detects CO, it is not specific only to CO; for dedicated CO detection, an MQ-7 sensor is often recommended.

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