The MQ-4 Natural Gas Sensor is a low-cost, highly sensitive semiconductor gas detection module designed for monitoring methane (CH₄) and natural gas in domestic, industrial, and portable gas detection applications. Built around the MQ-4 sensor with a tin dioxide (SnO₂) sensing layer, this module offers high sensitivity to methane while maintaining strong anti-interference capability against alcohol and other interfering gases. It is an ideal solution for household gas leak alarms, industrial combustible gas detectors, and portable gas detection instruments.
At the heart of the module is the MQ-4 sensor element, whose conductivity increases as the concentration of methane rises. In clean air, the sensor exhibits low conductivity; when exposed to methane or natural gas, its resistance drops, producing a measurable change in output. The module provides two independent outputs: an analog output (AO) that varies continuously with gas concentration for trend monitoring, and a digital output (DO) that switches when the concentration exceeds a user-adjustable threshold set by the onboard potentiometer. This dual-output design makes it suitable for both quantitative trend analysis and simple threshold-based alarm triggering.
The module operates from 5V DC with a typical current consumption of approximately 150mA. It is compatible with Arduino, ESP32, and other 5V microcontrollers; Raspberry Pi users require an external ADC. The board features a compact form factor and an onboard LED indicator that provides visual feedback for power and digital output status.
Important Note: The MQ-4 requires a significant preheat time for stable operation. New sensors should be powered on for not less than 48 hours in clean air before initial calibration. After each power-up, allow adequate time for the heater to stabilize. The sensor is not a calibrated industrial-grade detector and should not be used as a sole life-safety device. Its sensitivity degrades over time, and periodic replacement is recommended for critical applications. The sensor surface becomes hot during operation — avoid touching it. The module is not waterproof and should be kept dry.
Whether you are building a home gas leak alarm, an industrial methane detector, or an educational sensor project, the MQ-4 module provides a reliable, affordable solution for methane and natural gas detection.
Features
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MQ-4 SnO₂ semiconductor sensor — High sensitivity to methane (CH₄) and natural gas
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Strong anti-interference — Resistant to alcohol and other interfering gases
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Dual output — Analog (AO) for concentration trends, Digital (DO) for threshold alarms
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Adjustable threshold — Onboard potentiometer sets the digital output trigger point
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Wide detection range — 300–10,000 ppm for methane
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5V operation — Compatible with Arduino, ESP32, and other 5V microcontrollers
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LED indicators — Power and digital output status feedback
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Compact form factor — 32 × 20mm PCB for easy integration
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Long lifespan — Specified for up to 10 years under proper operating conditions
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Wide application range — Household gas alarms, industrial detectors, portable instruments
Technical Specifications
Usage
Getting Started
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Connect power — Connect VCC to 5V and GND to ground. The onboard power LED should light up.
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Connect outputs — Connect AO to an analog input on your microcontroller (e.g., A0 on Arduino) and DO to a digital input if threshold detection is needed.
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Preheat — Allow the sensor to warm up. For first-time use, power it in clean air for not less than 48 hours for best accuracy. For normal use, wait at least 5–10 minutes before taking readings.
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Calibrate (recommended) — In clean air, note the analog reading. Adjust the onboard potentiometer so the DO output switches just above this baseline.
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Read data — Use analogRead() for concentration trends, or digitalRead() for threshold-based alarms.
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Implement control logic — Trigger buzzers, valves, or notifications when the sensor value exceeds your defined threshold.
Pin Connections
Example Arduino Code (Basic Reading)
#define MQ4_AO A0
#define MQ4_DO 8
void setup() {
Serial.begin(9600);
pinMode(MQ4_DO, INPUT);
}
void loop() {
int analogValue = analogRead(MQ4_AO);
int digitalState = digitalRead(MQ4_DO);
Serial.print("Gas Level: ");
Serial.print(analogValue);
Serial.print(" | Alarm: ");
Serial.println(digitalState == LOW ? "TRIGGERED" : "Normal");
delay(1000);
}
Typical Applications
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Household gas leak alarms — Detect natural gas leaks from stoves, water heaters, and pipelines
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Industrial combustible gas detectors — Monitor methane in workshops, boilers, and chemical facilities
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Portable gas detection instruments — Handheld methane detectors for field work
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Educational STEM projects — Teaching analog sensing, gas detection, and calibration principles
Notes for Business Buyers
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Preheat is essential — The 48-hour initial burn-in is critical for stable readings; factor this into production testing timelines
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Not a precision instrument — MQ sensors provide relative trend data, not exact ppm readings for specific gases
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Sensor lifespan — Specified for 10 years under proper conditions, but practical lifespan depends on exposure to contaminants
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Suitable for bulk purchasing — Ideal for gas alarm manufacturers, educational kit suppliers, and industrial safety product developers
Q: What is the MQ-4 sensor used for?
It is a gas sensor for detecting methane (CH₄) and natural gas in household gas leak alarms, industrial combustible gas detectors, and portable gas detection instruments.
Q: What is the difference between the analog and digital outputs?
AO provides a continuous voltage that changes with gas concentration for trend monitoring. DO switches when the concentration exceeds the onboard potentiometer threshold, ideal for simple alarms.
Q: Why does the sensor need a long preheat time?
The SnO₂ sensing element requires heating to reach stable operating temperature. Winsen specifies a preheat time of not less than 48 hours for reliable operation.
Q: Can I measure exact ppm with this sensor?
Not accurately without calibration. The MQ-4 is non-selective and provides relative trends. For quantitative measurement, you need calibration curves and cross-sensitivity compensation.
Q: What voltage does the module require?
It operates from 5V DC with approximately 150mA current consumption.
Q: Does the sensor respond to other gases?
The MQ-4 has high sensitivity to methane and strong anti-interference to alcohol and other gases. However, it may still respond to other combustible gases.
Q: Is the sensor safe to touch?
No. The sensor surface becomes hot during operation due to the internal heater. Avoid touching it.
Q: Can I use this module with a Raspberry Pi?
Yes, but the Pi lacks a built-in ADC. Use an external ADC (e.g., MCP3008) to read the AO output.
Q: How long does the sensor last?
The sensor is specified for up to 10 years under proper conditions, but practical lifespan depends on exposure to contaminants.
Q: Can I purchase in bulk for a product development project?
Yes. This module is suitable for bulk purchasing by gas alarm manufacturers, educational kit suppliers, and industrial safety product developers.
