MQ-131 Ozone Sensor low output voltage problem

Using Arduino Sensors
1

Hi everyone,

I’m having an issue with the MQ-131 ozone sensor. From what I understand, when the sensor is powered on and there’s no ozone present, the output voltage should be around 4V. However, I’m only getting a reading of 0.2V to 0.3V.

I’m supplying the sensor with 5V as recommended.

  1. What could be causing this low output voltage, and how can I fix it?
  2. Also, how can I properly calibrate the MQ-131 sensor if I don’t have access to any other equipment for calibration?

Any advice would be greatly appreciated.

Thank you!

2

Are you using the actual sensor or are you using one of the dozens modules which have the sensor. Makes a difference. Did you leave it heating for the recommended time. Perhaps 72 hours or more depending how long it has been since it was last used.

3

Yes, I’m using the actual sensor with its board, and there are no other modules at the moment that I need to measure ozone.

Thank you very much for your advice @Paul_KD7HB . I am currently preheating the ozone sensor, and I will check it again after 48 or 72 hours.

If the sensor is not preheated, could the ozone readings be less accurate?

4

Where did you see this information?

5

I saw the information from the MQ-131 Ozone Sensor Manual as attached below.

chrome_jngF1f8pIv
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My ozone sensor came with its board, so it's not just the O3 sensor. Now I’m wondering: does the board affect the output voltage? @jim-p

6

I see this in the datasheet. RL = 1M

image
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7

Consider if you disclose the data sheet for the actual board you have in your hand, we might have a clue as to how to answer your questions.

8

WhatsApp Image 2024-12-02 at 11.10.58
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I dont have the data sheet for the ozone sensor. The data sheet I have is for the ozone sensor, which is not with the module.
mq131-h (2).pdf (514.3 KB)

I looked for it on the internet, but I couldn't find the ozone sensor data sheet for this module. Could you please help me? @jim-p @Paul_KD7HB

I have heated this module for more than 4 days, but the output voltage is still at 0.2 V in the absence of ozone.

9

Are you connected to the board Analog output and Ground?
How are you measuring the voltage?
What is the power source for the 5V?

However, none of this may matter since you have no way of calibrating.