MQ-2 analog readings always 1023

I am not sure if I am really that dumb or my MQ-2 sensor is faulty.

I have connected my MQ-2 FC-22 board to Arduino. It already has prepared pins.

I have also noticed that there are more models with different PIN order. I have double checked my pin connections, that should not be the problem.

  • VCC = Arduino 5V
  • GND = Arduino GND
  • D0 = not connected
  • A0 = Arduino Analog Pin A0

My source code is really simple

Serial.println(analogRead(A0));

I always see 1023 which is the maximum possible value. Sometimes 1022. According to the datasheet low gas means low sensor value. High sensor value means high gas in the air. I dont believe that my home is built above coal mine.
I believe the sensor does not need some extra callibration or pre-heat time since it always displays the maximum value. Or do I have to wait 48 hours for pre-heat before I get some serious readings?

Any ideas? Can the sensor be faulty?

Thanks!

Connect it and adjust the potentionmeter until the value is about 100...500.
Let it on for 24 hours (in the datasheets dat I read, I read about 24 hours).
The sensor should get warm, since there is a heater inside.
After the 24 hours, adjust it again for a value of about 100...500.

Is there a schematic for that module ?

Try blowing gently towards the sensor or light a match and blow that gently towards the sensor. The value should change.

If everything fails, perhaps the sensor or the module is broken.