SC4 Electrochemical Gas Sensor Module O2 CO & H2S UART Output Pin Type (New)

The SC4 electrochemical gas sensor module is a compact, calibrated sensing board that measures a single target gas oxygen (O2), carbon monoxide (CO) or hydrogen sulfide (H2S) and streams the concentration as a digital UART signal at 3.3 V logic level.

Each module pairs a YYS electrochemical cell with a signal-conditioning PCB and a 4-pin 2.54 mm header, so it can be wired straight to a microcontroller such as an Arduino, ESP32, STM32 or Raspberry Pi for real-time gas monitoring.

Key Benefits of the SC4 Gas Sensor Module

• Digital output, no analogue calibration work the module processes the cell signal on-board and sends a ready-to-read concentration value over UART.
• Three gas options on one platform choose the SC4-O2, SC4-CO or SC4-H2S version; all share the same pinout and communication protocol, so firmware can be reused.
• Stable, linear readings temperature compensation and strong anti-interference design deliver consistent, linear output.
• Low power, long service life low current draw and an expected service life of more than 24 months (O2 version) suit battery-powered and continuous monitors.
• Small footprint approximately 23 × 25 × 16.5 mm, easy to fit into handheld detectors and compact enclosures.

Features of the Electrochemical Gas Detection Module

Electrochemical Sensing Technology

• High sensitivity and high resolution electrochemical cell
• Temperature compensation for more accurate readings across the operating range
• Excellent linear output and anti-interference ability

UART Serial Interface

• UART output at 3.3 V level 9600 baud, 8 data bits, 1 stop bit, no parity check
• Automatic data upload: one 9-byte data frame per second (header, high byte, low byte, checksum)
• Concentration = (high byte × 256 + low byte) × resolution

Pin-Type (Header) Connection

• 4-pin straight header, 2.54 mm pitch plugs into breadboards, jumper leads and standard sockets
• Pin 1: Vin (4.2–5.5 V) ·
• Pin 2: UART TXD (0–3.3 V data output) ·
• Pin 3: UART RXD (0–3.3 V data input) ·
• Pin 4: GND
• PCB thickness 1.2 mm with mounting holes (1 mm radius) for secure installation

 Specifications : SC4 Gas Sensor Module

Which SC4 Variant Do I Need?

• SC4-O2 Oxygen Sensor Module oxygen concentration and oxygen-depletion monitoring, O2 analyser prototypes, confined-space and enclosure air checks.
• SC4-CO Carbon Monoxide Sensor Module CO leak detection near combustion equipment, garages, boiler rooms and indoor air-quality monitors.
• SC4-H2S Hydrogen Sulfide Sensor Module H2S detection in sewers, wastewater, biogas, livestock and laboratory environments.

Applications & Use Cases

• Portable and fixed gas detectors and alarm systems
• Oxygen monitoring in laboratories, storage rooms and equipment enclosures
• Indoor air-quality and environmental monitoring stations
• Industrial safety, confined-space entry and process monitoring
• IoT, smart-building and data-logging projects
• Engineering, research, education and Arduino/ESP32 prototyping

Installation & Care Tips

• Power the module from a regulated 4.2–5.5 V supply and connect TXD/RXD to your controller’s 3.3 V UART pins.
• Allow the specified warm-up time before taking readings.
• Keep the gas inlet (white membrane) clean and unobstructed; avoid condensation, solvents and silicone vapours.
• Store unused O2 modules at 0–20 °C to maximise service life.
• This is a component-level sensor module for integration and development; it is not a certified medical or life-safety device on its own.

You Will Receive

• 1 × SC4 electrochemical gas sensor module (O2, CO or H2S – as selected), pin-type header version

Frequently Asked Questions

What is the SC4 electrochemical gas sensor module?

It is a small digital gas sensor board that combines an electrochemical cell with processing electronics and outputs the measured O2, CO or H2S concentration over a 3.3 V UART interface.

Does the SC4 sensor module work with Arduino?

Yes. Connect Vin and GND to a 4.2–5.5 V supply and wire TXD/RXD to a serial port at 9600 baud. With 5 V boards, the module’s 3.3 V TXD signal is normally read without issue, but a level shifter is recommended on the RXD line.

How often does the module send data?

The module automatically transmits one 9-byte data frame every second, so no request command is needed for continuous readings.

How do I calculate the gas concentration from the UART data?

Multiply the high data byte by 256, add the low data byte, then multiply by the resolution of your variant (for example 0.1% VOL for the SC4-O2).

What is the measuring range of the SC4-O2 oxygen sensor?

The SC4-O2 measures 0–30% VOL oxygen with 0.1% resolution and tolerates a maximum load of 35% VOL.

How long does the SC4 gas sensor last?

The SC4-O2 module has a rated service life of more than 24 months under normal operating conditions. Life depends on gas exposure, temperature and humidity.

Is the pin type the same for all three gases?

Yes. All three variants on this listing use the same 4-pin, 2.54 mm straight header and identical pin assignment, so you can swap gas types without redesigning your board.

Related Oxygen & Gas Sensors

Looking for replacement cells or other oxygen sensing parts?

Browse the UK City MOX-4 Oxygen Sensor, the UK City MOX2 Oxygen Sensor, the Envitec OOM204 Medical Oxygen Sensor, the MAX-250E External Oxygen Sensor and our MOX / AO Series Oxygen Sensor range.