MH-Z19C NDIR CO2 Sensor Module (400-5000ppm) - Wired Type with Cable

Specifications

• Model: MH-Z19C.

• Sensing Method: NDIR (Non-Dispersive Infrared).

• Target Gas: CO2 (Carbon Dioxide).

• Measurement Range: 400 ~ 5000 ppm.

• Accuracy: ±(50ppm + 5% reading).

• Warm-up Time: < 1 Minute (Significant upgrade over MH-Z19B).

• Output Signal:

  • UART: Serial (TTL 3.3V).

  • PWM: Pulse Width Modulation.

• Working Voltage: 4.9V ~ 5.1V DC.

• Connector: 7-Pin JST (Cable Included).

Key Applications & Projects

• Smart HVAC: Automatically trigger exhaust fans in offices or schools when CO2 exceeds 1000ppm.

• Mushroom Farming: Fungi release massive amounts of CO2; monitor levels to prevent suffocating the crop (or the farmer!).

• Demand Control Ventilation (DCV): Save energy by running AC fans only when people are actually in the room (detected via breath CO2).

• Sleep Quality: Monitor bedroom CO2 levels—high CO2 at night is a leading cause of morning grogginess.

Project Evolution

• The Bottleneck: The old MH-Z19B took 3 minutes to stabilise every time you turned it on.

• The Upgrade: The MH-Z19C is ready in less than 60 seconds. This makes it viable for battery-powered devices that wake up, take a reading, and sleep again to save power.

• Effort Level: Intermediate. Requires connecting 4 wires (VCC, GND, TX, RX) and using a standard library.

Virtual Technician & Setup Guide

• Power Supply: This sensor is sensitive to voltage ripples. Use a clean, regulated 5V DC source. Do not power it directly from a noisy 5V pin on a cheap Arduino clone if possible.

• Calibration: The sensor features ABC (Automatic Baseline Calibration). It recalibrates itself every 24 hours, assuming the lowest reading is 400ppm (fresh air).

  • Note: If using in a Greenhouse (where CO2 is always high), disable ABC via software command.

• Placement: Do not place the sensor in direct sunlight or near a heat source, as temperature fluctuations can affect the gas density readings.

Accessories & Compatibility

• Included: 1x MH-Z19C Sensor, 1x 7-Pin Interface Cable.

• Required: Microcontroller (ESP32/Arduino) with UART support.

• Compatible: Works with existing MH-Z19 Arduino libraries (backwards compatible).

Helpful Tutorials & Resources

• MH-Z19C CO2 Sensor_Datasheet

• Arduino Library for MH-Z19

Frequently Asked Questions (Technical SEO)

• What is the difference between MH-Z19C and MH-Z19B? The C version is the newer model. It has a faster warm-up time (<1 min vs 3 mins), lower power consumption, and is generally more stable. The pinout and commands are largely compatible.
• Does this replace the MH-Z19B? Yes, Winsen has phased out the "B" version. The "C" is the direct replacement.
• Is the cable included? Yes, this "Wired Type" comes with the 7-pin connector cable, so you don't need to solder the terminal pins.
• How accurate is it? It has an accuracy of ±(50ppm + 5% of reading). For a 1000ppm reading, the error is roughly ±100ppm, which is excellent for air quality monitoring.
• Does it work with 3.3V microcontrollers? Yes, the UART (TX/RX) logic level is 3.3V, making it perfectly safe for ESP32, ESP8266, and Raspberry Pi. You still need 5V to power the VCC pin.
• Can I use it outdoors? It is designed for indoor use. High humidity or direct water contact will damage the optical chamber.
• How do I calibrate it manually? Connect the "HD" pin to Ground (GND) for 7 seconds while the sensor is in fresh outdoor air. This resets the zero point to 400ppm.
• What is the lifespan? The expected lifespan is over 5 years of continuous operation.
• Can I use it to detect fire? Technically yes, as fires release CO2, but it is slow compared to smoke detectors. It should not be your primary safety device for fire.
• Does it measure Carbon Monoxide (CO)? No. It is specific to Carbon Dioxide (CO2). It will not detect the poisonous Carbon Monoxide gas.
• Why is the reading 400ppm all the time? If the reading is stuck at 400ppm, the sensor might have been calibrated in a room with high CO2 (mistaking high CO2 for 400ppm). Take it outside to fresh air and trigger a manual calibration.
• What is the range? It measures from 400ppm (fresh air base) up to 5000ppm. (Note: Human breath is ~40,000ppm, so don't blow directly on it to test, it will max out instantly).
• Is the library different from MH-Z19B? Most "MH-Z19" Arduino libraries work seamlessly with the C version as the command set is standard.
• Does it support I2C? No, the standard MH-Z19C supports UART and PWM only. It does not have an I2C interface.
• Can I turn off the ABC logic? Yes, you can send a specific Hex command via Serial to disable Automatic Baseline Calibration if your application requires it (e.g., Greenhouses).