MQ Gas Sensor - yesterday performed flawlessly; today it's signal is maxed out

Device: Flying Fish MQ-5 gas sensor
Application: Propane gas detection
Processor: Arduino UNO WiFi Rev2

Yesterday:
After powering device up and letting it set for an hour the sensor responded
immediately to sensing a small amount of propane released in its vicinity.
Baseline w/ no gas: .434 vDC at UNO input equating to a value of "113"on serial monitor.
The potentiometer was set to trigger the digital output at around "300."
Upon sensing the gas the sensor immediately went to 800 - 1000 and then
slowly fell back to to 120- 130 with gas removal.

Today:
Unit was disconnected overnight. Upon applying power the sensor immediately
went to around "1000" on the serial monitor, w/ no gas presence.
Device has been energized for over an hour and the output voltage remains very
high at around 4.7 vDC;

Has anyone used these Flying Fish sensors for extended periods of time and they
remained reliable? They are certainly inexpensive and I am wondering if it is typical for them to drift and lose their accuracy.
If anyone has used a different gas sensor with success I am curious to know what it is.
I may get another Flying Fish just to see if this one was a fluke.

Also posted at >> https://forum.arduino.cc/t/flying-fish-mq-gas-sensor-worked-great-yesterday-today-it-is-maxing-out/1064873

That was deleted and moved to this subforum.

After any significant period of being disconnected, the readings from an MQ sensor are meaningless until it is burned in again. This can take anywhere from a few hours to 72 hours. The sensor heater is intended to be powered up continuously.

Lots of good info on those sensors in this tutorial: https://web.archive.org/web/20180513090020/http://www.maskau.dk/projects/electronic-nose

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.