MH-Z19E NDIR CO2 Sensor Module (400-5000ppm) - Wired Type with Cable

Specifications

• Model: MH-Z19E.

• Technology: NDIR (Non-Dispersive Infrared).

• Target Gas: CO2 (Carbon Dioxide).

• Detection Range: 400 ~ 5000 ppm.

• Accuracy: ±(50ppm + 5% reading).

• Output Signals:

  • UART: Serial (TTL level 3.3V).

  • PWM: Pulse Width Modulation (Duty cycle represents concentration).

• Working Voltage: 4.9V ~ 5.1V DC.

• Preheat Time: 1 Minute.

• Response Time: T90 < 120s.

Key Applications & Projects

• Smart Ventilation: Turn on fresh air fans automatically when CO2 hits 1000ppm (the level where humans start feeling drowsy).

• Classroom Monitor: Build a "Focus Meter" to alert teachers when the room needs airing out.

• Greenhouse Automation: Optimise plant growth by maintaining high CO2 levels (up to 2000ppm).

• COVID/Health Safety: High CO2 levels indicate poor ventilation and a higher risk of airborne virus transmission.

Project Evolution

• The Bottleneck: Electrochemical sensors drift over time and need constant recalibration.

• The Upgrade: The MH-Z19E has ABC (Automatic Baseline Calibration). It automatically recalibrates itself every 24 hours based on the lowest CO2 level detected (usually fresh air at 400ppm). This makes it maintenance-free for years.

• Effort Level: Intermediate. Requires parsing Serial data or measuring PWM pulse width.

Virtual Technician & Setup Guide

• Calibration: The sensor comes with ABC enabled by default. For it to work, the sensor must be exposed to fresh outdoor air (400ppm) for at least 20 minutes once every 24 hours. If used in a constantly occupied room (like a greenhouse), you should disable ABC via software command.

• Voltage: It requires a stable 5V supply. If using a 3.3V microcontroller (ESP32), connect VCC to 5V, but the RX/TX pins are usually 3.3V tolerant.

• Warm-Up: The sensor needs about 1 to 3 minutes after power-up to stabilise. Ignore the readings during this start-up phase.

Accessories & Compatibility

• Included: 1x MH-Z19E Sensor, 1x 7-Pin JST Interface Cable.

• Compatible: Arduino, ESP8266, ESP32, Raspberry Pi (via Serial).

Helpful Tutorials & Resources

• MH-Z19E CO2 Sensor_Datasheet

• Arduino Library for MH-Z19

Frequently Asked Questions (Technical SEO)

• What is the difference between MH-Z19B and MH-Z19E? The "E" is the newer, smaller, and lower-cost version. Performance is nearly identical, but the "E" has a slightly narrower voltage tolerance (needs clean 5V).
• Does it measure Oxygen? No, NDIR technology is specific to CO2. It does not measure Oxygen or Carbon Monoxide (CO).
• How do I calibrate it? You can trigger a "Zero Point Calibration" (400ppm) manually by pulling the HD pin LOW for 7 seconds while the sensor is in fresh outdoor air.
• Can I use it with ESPHome? Yes! It is fully supported in ESPHome. Just connect the TX/RX pins and add the mh_z19 component to your YAML config.
• What is the "ABC" logic? Automatic Baseline Calibration. The sensor assumes the lowest reading it sees in 24 hours is "Fresh Air" (400ppm) and adjusts its zero point accordingly.
• Is the cable included? Yes, this "Wired Type" SKU includes the specific 7-pin cable, so you don't need to solder directly to the terminals.
• Can I leave it running 24/7? Yes, NDIR sensors have a long lifespan (5+ years) and are designed for continuous monitoring.
• Why is my reading stuck at 400ppm? If it's stuck exactly at 400, it might be in warm-up mode, or you might have accidentally calibrated it in a dirty environment. Put it outside and recalibrate.
• Does it detect smoke? No. For smoke detection, you need a particle sensor (like PM2.5) or a specialised smoke detector.
• What is the Logic Level? The UART (TX/RX) pins operate at 3.3V Logic, making it directly compatible with ESP32/Raspberry Pi. It works with 5V Arduino too (the RX pin is 5V tolerant on most Winsen modules, but a level shifter is safer).
• Can I use PWM instead of Serial? Yes, the PWM pin outputs a pulse ranging from 0ms to 1004ms. The length of the HIGH pulse corresponds to the CO2 ppm.
• Is it waterproof? No. The optical chamber must have airflow to work. Do not let water enter the gold chamber.
• Why are the readings fluctuating? CO2 is a gas that moves in pockets. Fluctuations are normal as air currents move past the sensor.
• Does it get hot? The internal IR lamp generates a tiny amount of heat, but the module should stay cool to the touch.